i have worked a combined several years at various pizza places delivering pizza. i have the business down to a T...unfortunately.
at least 2 bucks, and the driver won't be pissed...but 3 is solid. 4 and 5, you're recognized as a good tipper, and anything above five, you will definitely be remembered in the future. i had a few $20 tips in my day, but that was for BIG orders, and usually at a business.
it's a damn good job though, all i did was drive around town, listen to music, smoke weed, and i'd walk with like $40-50 in my pocket at the end of the night. plus, it's a perfect job if you got yourself a little side hustle too, if u yadida...
there are tons of ways to make extra money thru the restaraunt too...use your head. in all my experience driving, like 1% of the people ask for a receipt...so you can charge for shit that the restaraunt isn't charging you for, you feel me?? lol, good luck, do your thang