Read this brief example illustrating how data flows through this information system.

A large brick and mortar store uses an information system to speed up the process of calculating and collecting payment from its customers. Here is how it works. The customer provides a list of items they wish to purchase. The system then determines the price to charge for each item by looking up each item in the list of current discounts. If a promotional discount applies, the discount price is used to determine the price to charge. The next step in determining the price to charge is to search the product catalog for each item to see if it is taxable or not. When all items have been priced, the system sends the total purchase amount to the card reader to complete the remaining steps to collect payment.

Now match each item below with the role it plays in the data flow diagram for this scenario.