In the USA to tip a piza delivery man
of 15-20% should be given
in tip,no matter how much you are ordering.This is like a must because
it is his best efforts that he is delivering you it at time.By giving him that
he will remember that you are a good tipper and next time also he will bring it at time and make his customer hapy by providing best services.Before the man lives also you are supposed to pay attention that your delivery is correct,in this case you can reduce it,he will also remember this punisment
and next time will rectfy.