SAGINAW, Mich. - They had already clocked out for the day, one employee said, but an announcement over the PA system called them back: We need help tidying the purse department. Another employee said she would punch out for lunch but be asked to stop during her break and compare prices at a competing store or pick up some office supplies.

The complaints may seem like so much petty grumbling - 15 minutes of off-the-clock work here, an abbreviated lunch there. But when the company accused of incrementally shorting its workers of wages is Wal-Mart, the country's largest employer, with more than 1 million "associates" nationwide, the potential for free labor could add up to untold millions of dollars - out of the pockets of people who are already at the bottom of the pay scale and can least afford it.

That the phenomenally profitable retailer would make such nickel-and-dime intrusions on their time was bad enough, employees say, but what particularly rankled was how they would then have to ask over and over again simply to be paid for the extra work.

"I just got tired of asking," said Nadia Zufelt, testifying in a lawsuit she and other Michigan workers filed here against the world's biggest company, demanding compensation. "You feel like you're begging after a while."

"It was kind of a shock to think, is this happening to everyone who worked there?" Lindsay Armantrout said.

The two women are plaintiffs in a class-action lawsuit, one of about 30 similar cases that former employees have filed against Wal-Mart across the country in recent years. The suits charge that employees regularly had to work off the clock, and were sometimes even locked in their stores and prevented from leaving before finishing extra tasks.

Together, they cast a shadow on Wal-Mart's otherwise glowing economic performance - it is the darling of both consumers who flock to its stores for name-brand merchandise at low prices, and of Wall Street, where the chain's high profit margins and unparalleled growth make it the envy of its industry and a star performer in many a stock portfolio.

But Wal-Mart's success comes at a price, the plaintiffs claim.

"It has ridden the backs of its hourly employees to extreme profitability," the lawsuit filed here charges.

A big target

That Wal-Mart would draw litigation from its own workers was perhaps inevitable. The company has increasingly become a lightning rod for a range of critics, from anti-sprawl groups seeking to prevent big-box retailers from blighting their landscape, to anti-sweatshop activists who decry the store's use of cheap foreign laborers, to lawyers who have sued the company so frequently that it now draws more litigation than any entity except the federal government.

In many states, Wal-Mart is the single largest employer, a role that reflects how the nation's jobs continue to shift from manufacturing to service. The stores may bring hundreds of jobs to a community, but labor activists complain that they are not always good ones - pay averages less than $9 an hour, lower than the old, unionized manufacturing jobs that they replaced. Wal-Mart, though, has successfully rebuffed attempts to unionize its employees.

The company denies that it regularly makes employees work off the clock but concedes that there have been isolated incidents of this happening.

"It's wrong, and we don't tolerate it," said spokesman Bill Wertz, adding that the company has fired managers who have failed to pay employees for all the time they have worked. "We're very concerned, and we take these cases very seriously."

Mixed results

The suit in Michigan is similar to others filed elsewhere by workers seeking certification as a class to represent all Wal-Mart employees in their state. Plaintiffs have had mixed results.

Wal-Mart successfully beat class certification attempts in Ohio, Texas and Louisiana.

But a suit filed in Colorado was settled out of court after Wal-Mart reportedly agreed to pay $50 million. Similarly, employees won their case in Oregon, where a federal jury decided last month that the company violated wage-and-hour laws. A subsequent jury will determine the amount of damages Wal-Mart will pay.

Wertz said Wal-Mart is likely to appeal that verdict.

Here in Michigan, a Circuit Court judge took testimony in November, then put the case on hold until later this month.

The company contends that most of its employees are pleased with their work conditions. Attorneys for the company have argued that the employees who have sued may have individual complaints against their respective managers but do not represent the entire class of Wal-Mart workers, as their lawsuits seek to do.

"There is nothing about this lawsuit that makes it appropriate for class action treatment," Wal-Mart's attorneys wrote in a response to the suit here. "Even the named plaintiffs share virtually nothing in common with each other, except that they were all solicited to join this suit by the same counsel through the same '800' number."

In the thousands of pages of documents that make up the case's files, former Wal-Mart employees describe a workplace decidedly at odds with the company's carefully crafted image of stores with friendly greeters at the door and an atmosphere of small-town warmth.

'A little piddly thing'

Instead, the plaintiffs described jobs where the company's vaunted ideals of having the lowest prices and the highest customer service came at their expense: They had to pester managers for the breaks, to which they were entitled. They could be interrupted during lunch to handle something in their department. Even clocking out for the day didn't end their responsibilities - they were expected to assist customers who stopped them on their way out the door or other departments that needed help.

And then they were brushed off when they tried to get paid for the extra tasks, former employees testified.

"Let's catch it later," Zufelt said one supervisor told her when she asked to be compensated for working during her lunch hour. Or, "It's a little piddly thing to worry about."

Employees clock out for lunch and then clock back in when they return, so they are not paid for the break. Nonetheless, said Zufelt, who worked at a store in Muskegon, Mich., managers asked her to pick up computer paper at Staples while she was out for lunch, or to compare prices with a competing store.

"I was leaving the store one day to go to lunch," she said, when a manager stopped her to ask a favor. "He wanted me to stop at Meijer's and double-check a cologne to see if we were compatible with them."

Only work around

Employees said they put up with the treatment because they needed the work - in some areas, Wal-Mart is often one of the only large employers around, particularly for those without specialized job skills.

"I was pregnant, it was a job, and they were hiring," said Armantrout, who was hired in a Wal-Mart in Grandville, Mich. in 1998.

Because she had previously worked in fast-food restaurants, she was assigned to the store's snack grill, making $6.75 an hour. Armantrout said she often worked straight through her shift because she wasn't allowed to leave the grill unattended.

"Sometimes it would be, 'We don't have anyone to cover for you,' or 'I'll find somebody,'" she said, "but they didn't."

Armantrout said in a deposition that she would sit at one of the snack bar booths to rest if there were no customers but was reprimanded for that.

"Ain't there something you can clean?" she said a manager asked her.

'Tired of asking'

Her wages were shorted in other ways, Armantrout said. Sometimes, employees would punch out for the night, but an announcement would come over the public address system calling everyone to a department that needed straightening up so that it would be presentable when the store opened again.

Even if they didn't want to stay late and help, employees were stuck in the store because the doors would already be locked for the night, and they would have to wait until a manager agreed to let them leave, she said.

A supervisor would record the amount of extra time they worked in a notebook, she said, promising to adjust their paychecks. But Armantrout said she checked her paycheck a couple of times after working off the clock but didn't find any extra compensation.

"They said they would take care of it," she said, "and I'd just get tired of asking."

Armantrout left Wal-Mart after six months and got another food service job, but she didn't really grow angry about how she was treated at the store until later. She remembers seeing a television show about Sam Walton, the late and legendary founder of Wal-Mart, and said she was shocked by how much money he made and his heirs continue to make. (Five of the 10 richest Americans are members of the Walton family, according to Forbes magazine.)

Her mother happened to see a commercial in which a law firm, which has sued Wal-Mart in several states, was seeking employees with wage complaints against the store and wrote down its toll-free number.

Despite her involvement in the suit, Wal-Mart remains an unavoidable part of her life: She now works for a cell phone company in a booth housed in a Wal-Mart in Bay City, Mich., and that is also where she tends to shop.

"There are things you can find there cheaper than anywhere else," Armantrout said with a shrug.