Most tips I see are not "fractions of a penny" but rather the standard seems to be 1000 bits which is like 32 cents. I often see people tip a dollar or more.

Secondly, I can never understand why some people get so offended by someone giving them a small amount of money. When you go to the coffee shop to buy a $2.40 coffee and are given $0.60 in change are you insulted by the cashier for thinking you needed that 60 cents?