"Communication around it is key," Miller said.

Yet some parents still do not participate. For many programs, parents need to re-register their cards and school choices each year, Underwood said.

Parents also need to know their store card numbers to enroll, she said.

"So few people have that anymore," she said. "Most just enter their phone number for the discount and don't have their cards handy."

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Store hotlines can usually provide card numbers if parents need them, she said.

Others are concerned participating in the program will take away from their regular shopping rewards, like food and gas discounts.

Not true, said Sara Toscano, PTA president at Relay Elementary School, which received $1,600 from Giant and $469 from Target last year.

"It all adds up in the end," Toscano said. "It's just a matter of taking five minutes to sign up their card."

Lansdowne Elementary School Principal Jane Lichter, said the school administration hasn't pushed the rewards programs.

The school participates in Box Tops collections and received some money from Safeway last year after a parent submitted the school's name.

But it doesn't have much involvement with the Giant program, she said.

According to Giant, the school received $93 last year through the store's rewards program.

"The potential is there," Lichter said. "We just have to collect on that."