Вы могли бы сделать это хорошо со словарями, но без использования по-прежнему есть много способов сделать это, варианты бесконечны, вот одна идея
def get_bills(change, value):
if change//value > 0:
bills = change//value
change -= bills * value
return bills, change
else:
return 0, change
cost = float(input('Cost: '))
paid = float(input('Amount Paid: '))
while paid < cost:
paid = float(input('Amount Paid: '))
change = paid - cost
hundreds, change, = get_bills(change, 100)
fifties, change, = get_bills(change, 50)
twenties, change = get_bills(change, 20)
tens, change = get_bills(change, 10)
fives, change = get_bills(change, 5)
ones, change = get_bills(change, 1)
quarters, change = get_bills(change, .25)
dimes, change = get_bills(change, .1)
nickels, change = get_bills(change, .05)
pennies = round(change * 100)
print(f"Hundreds: {hundreds}, Fifties: {fifties}, Twenties: {twenties}," +
f" Tens: {tens}, Fives: {fives}, Ones: {ones}, Quarters: {quarters}," +
f" Dimes: {dimes}, Nickels: {nickels}, Pennies: " +
f"{pennies}")