Rule #6: Give Change in Singles
If the bill is $14.95, and the customer hands you a twenty, do not bring back a nickel and a $5 bill. When you do this you convey one of the following:
A) your service is worth a mere 5 cents
B) you expect a 33% tip
C) the customer's time is not valuable and it's his or her responsibility to ask for additional change
Bring back a nickel and five singles, and trust that you'll get the gratuity that you deserve.