a couple times. I just don't feel right taking the money without asking. customers are always real nice and thank me for checking. I understand some people are just good tippers and I have regulars who always tip 100% so I know not to ask them every time. I just don't see the harm in checking. like if a bill is 30 and they pay with 3 20's, maybe they meant to give me 40 and not 60.