Why does this keep happening to me? We went out for lunch again on Friday. I got a BBQ sandwich, mac & cheese, and a water which came to a total of $8.03. I gave the waitress a $20 when she came to pick up our checks. When she brought all the checks back, mine had $11 in it: 6 one's and 1 five. Wait a minute...$20 - $8.03 = $11.97. Now I've seen people bring back $12 in that situation, but never $11. I really felt like not leaving any additional tip. After all, she already took 97 cents....