I don't know if I am being a complete bitch or not, but your idea of "not writing in the tip amount" in #1 is not exactly true. I'm a waitress and bartender and when (drunk) customers fill out their tab slips, we have to adjust the tip amount on our credit card machines, and according to payment regulations, we are supposed to adjust our tips according to the "tip" portion, not the "total" portion... If you ever got drunk and wanted to leave a $10 tip but accidentally left a $100 tip in the total (exaggeration, but you get the point) you could be screwing yourself... From the flip side of the industry, I recommend filling out the "tip" line.