示例 Process sale scenario Cashier System makeNewSale Simple cash-only Process sale scenario 1. Customer arrives at a pos checkout loop丿 more items with goods and/or services to purchase enterltem(itemID, quantity) 2. Cashier starts a new sale 3. Cashier enters item identifie description, total 4. System records sale line item and presents item description, price, and running total Cashier repeats steps 3-4 until indicates done end Sale 5. System presents total with taxes calculated 6. Cashier tells customer the total and total with taxes asks for payment 7. Customer pays and System handles payment makePayment(amount) change due, re示例 : Cashier :System Simple cash-only Process Sale scenario: 1. Customer arrives at a POS checkout with goods and/or services to purchase. 2. Cashier starts a new sale. 3. Cashier enters item identifier. 4. System records sale line item and presents item description, price, and running total. Cashier repeats steps 3-4 until indicates done. 5. System presents total with taxes calculated. 6. Cashier tells Customer the total, and asks for payment. 7. Customer pays and System handles payment. ... enterItem(itemID, quantity) endSale makePayment(amount) description, total total with taxes change due, receipt makeNewSale loop [ more items ] Process Sale Scenario