Sales clerks in a retail store are assigned specific cash register, they are given a cash drawer containing $100 in change at the beginning of their shift. They are required to record the amount of each purchases in the cash register. The cash register records identifcation and price for each item purchased. Cash payments are collected from customers and placed in the cash drawer. A copy of the cash register sales slips is given to the customer. At the end of each shift the employee takes the cash drawer and cash register tape to a supervisor who counts the cash, verfies the sales, and signs an approval form. The sales clerk also signs the form that identifies the amount of the cash and amountof the sales for the day. Why are these procedures used and how do they provide effective internal control?