Answer:
So you have:
$10 bills --- 9
$1 bills ---- 9
$0.10 ----- 9
The maximum amount of change that you can give is al of that together.
9*$10 + 9*$1 + 9*$0.10 = $99.90
(supposing that a person only hands you a $100 bill because he needs to have smaller bills for something).
The minimum change that you can give is just a dime, so it is $0.10
If you need to give $0.07 to someone, you should give him a dim ($0.10)
Because is the smaller that you have, and if we round $0.07 it would be rounded up to $0.10.