Last week I paid for my coffee with a $100 bill and got shorted $10. I doubt the cashier was risking getting fired over $10, so I have to assume she just didn't know how to count change. This morning, a cashier at Arco surprised the crap out of me and counted back my change properly. It doesn't seem to be related to the "classiness" of the shop, or even the age of the cashier -- properly counting back change has somehow become a lost art.