Programming challenge description: the goal of this challenge is to design a cash register program. you will be given two decimal numbers. the first is the purchase price (pp) of the item. the second is the cash (ch) given by the customer. your register currently has the following bills/coins within it: 'penny': .01, 'nickel': .05, 'dime': .10, 'quarter': .25, 'half dollar': .50, 'one': 1.00, 'two': 2.00, 'five': 5.00, 'ten': 10.00, 'twenty': 20.00, 'fifty': 50.00, 'one hundred': 100.00 the aim of the program is to calculate the change that has to be returned to the customer.