Petty See, Petty Do
This person told a story that every cashier can relate to. Basically, it goes like this. The OP, as a cashier, would stick their hand out, palm-side up, when receiving payment from customers. Some people would completely ignore the hand and place their dollar bills on the counter. No harm, right?
Except that there was harm, at least to the OP’s ego, and we totally get it. So, if you’re going to ignore their hand when asking for payment, they’re going to ignore yours when asking for your change. This form of revenge is so petty that we absolutely love it.