I understand why they might ask "Can I get you any change?" Some people will pay with cash and leave just enough for the meal plus tip. I try to do that if I have the right change. What I don't like is when the server brings back a $10 bill and a quarter change from a fifty for a meal that was $39.75. I had one absolutely lousy waiter do that to me, and he got tipped a quarter. After having waited 10 minutes for him to take the drink order, then the meal order, then for the check after I managed to flag him down for it, I wasn't about to wait another 10 minutes for him to come back to ask him to break the ten, and another 10 minutes for him to come back with the change, and I sure wasn't going to tip him $10.