@Sturgis,
That whole thing is stupid - my daughter's class won and they got a pizza party.
We had the whole extended family clipping box tops - many of these things are for trash bags and other stuff - we had them from our refried beans. There are also cereals that do not have much sugar.
The schools have raised a lot of money simply by asking families to bring these in - I didn't buy stuff simply for the box tops - if my kid asked for something that I didn't approve of I would simply say no. I just clipped those box tops off anything I happen to buy and stiff we ended up with hundreds after having other family members just do the same thing.
You cannot believe how much a school can get with these things - and then parent volunteers work with the school to send all the stuff in. It helps keep costs down for things like computers and field trips that the school gets a little more money for.