When I worked at Wing Zone (man, that job sucked) as a delivery driver, I also had to take orders, do prep work (chop veggies, make tea, and make salads), and cook food in the kitchen (not to mention cleaning up afterwards). Pretty much I had to do everything except actually be a manager. On top of that, I had to drive out in my own car to make deliveries. Generally speaking, most folks seemed to tip around $2. Sometimes they’d tip more, sometimes they’d tip less. On rare occasion, people wouldn’t tip anything.
I’ve actually been chased by a one-legged drunk man who wanted pizza from me, in a rather bad neighborhood in the middle of the night. That was freaky as hell.
But yeah, there was a $1 delivery charge, 70 cents of which went to us (the other 30 cents went to… uhm… I dunno, the phone company maybe?). We also got paid $5.75 an hour, which at the time was some small amount above minimum wage in Texas. No idea how much I spent on gas at the time, but I also had to provide and maintain my own vehicle. While I worked there, I had to get an oil change, replace a flat tire, and replace a missing oil cap that they forgot to replace after the oil change, all in a one month period.
By far the best people to deliver to are delivery drivers from other restaurants (For some reason, none of us ever ordered from Wing Zone when we were at home). Met a great bunch of Dominos delivery guys one night who told me the best way to get through their crazy labrynth-like apartment complex and tipped me well. We also got into a debate over which place treated us better. In College Station, TX, Dominos paid better, but Wing Zone got hot bags with handles.
So yeah, tip what seems fair, but certainly tip. $2 is a bare minimum IMO, but then that was my opinion before I worked as a delivery boy. I usually tip the pizza guy $4 (in advance normally, since I pay online) when I order, usually a medium pizza and some cheese bread and a drink. Comes out to about a 13 percent tip if my math isn’t all wrong.