As a 6-year veteran of the delivery industry from high school through finishing my bachelor's, I always use a base tip of $3 and go up according to A) how far away am I? B) is the weather bad? and C) how demanding was I (specific time, call ahead so I can meet you at the door, etc). I've always wondered, with all of our information on your restaurant computer, do you have a little comments section like the doctors did for Elaine on Seinfeld? Drivers come back and enter a note, "poor tip again" or am I just crazy? I entered stuff like that all the time. "Tips huge, give him a deal", "guaranteed stiff", etc. People who've been there a while remember every customer who orders regularly, and WILL prioritize orders and service according to how well you tip. I had a guy who gave at least $5 every time. When his order went out with 2 others, guess which was my first stop?