How many coins to make $0.50?

Sally buys $16.23 worth of groceries and pays with a $20 bill. What is the fewest number of coins she can get from the cashier?

How many coins to make $1.37?

What is the fewest amount of coins needed to make every amount from $0.01 to $1.00?

Vinit has 0 toonies, 1 loonie, 1 quarter, 2 dimes, 7 nickels, and 12 pennies. What is the fewest amount of coins he can use to make $1.56?