Tax

I buy fish food in bulk from a feed store. It's a great place. They have feed and supply for about any animal you could possibly have on a farm. They also sell guns. Feed and Guns. Can it get any better? Plus, their gun selection is great and the prices are amazing. Anyways, I buy my fish feed in 50lb bags, and they are $21.50. Every time I pay, the extremely old lady that owns the place asks me cash, check, or charge. I pay cash. She asks me if I want a receipt. I tell her no every time. And then she always says my total is $43 ( I buy two bags) and "Fish don't eat sales tax." And once I bought bird feed in bulk, cash, no receipt. Birds don't eat sales tax either.