Does the customer buying process end when a customer buys merchandise?

No, the buying process doesn't end after the customer buys the merchandise. There are several stall customer will go through after they get what they want. The store tries to put the sale item on their way back to check out and try to make the customer spend every bit of the dollar they can. Also they put the necessary items such as newspapers, magazines, gums, mints etc in a easy access place beside the checkout lanes so that they can spend more money.