How do I add a separator (comma ) to a number so that it prints. see program below :

packages = int(input('Enter the number of packages purchased: '))

cost = 99 * packages

discount = 0

if 10 <= packages <= 19:

discount = cost * 0.1

if 20 <= packages <= 49:

discount = cost * 0.2

if 50 <= packages <= 99:

discount = cost * 0.3

if packages >= 100:

discount = cost * 0.4

total = cost - discount

print('Discount Amount: $%.2f' % discount)

print('Total Purchase Amount: $%.2f' % total)