Wow wildbill24, I can't quite remember the ad except the ending where she see's her husband, one checkstand over, and she mouths the words "thank you" - that's all I remember.
But what was the store? Was it Walmart, or Target, or Office Depot?
Until someone else posts the correct information, here's an interesting link to station WALA-TV - FOX10 News from Mobile, Alabama/Florida Panhandle area.
http://www.youtube.com/watch?v=G5GkdYkFt9w
An old trick that always comes in handy is to take a backpack and load it up with school supplies but use a solar-powered calculator to add up the total as you shop, even if you're not going to buy the calculator. Use it then put it back after you're done with it.