The Checkout button is used when the customer is ready to pay for the transaction. The Checkout functionality works in tandem with a customer display device (also called a display pole). The display device shows the customer the taxes and total of their transaction and can help them decide the payment method they will use to complete the transaction.
When the Checkout button is enabled in the Configuration - Lanes screen, it appears in the Transactions button panel in the POS view.
While selecting a customer and selecting products to add to the transaction, the Checkout button appears on the Transactions button panel. On clicking the Checkout button, the customer can see the taxes and total on the display device.
Once the customer is ready to pay, click the Checkout button. The payment methods become visible and you can select a payment method.
NOTE: If you need to go back and change something about the transaction (e.g. change a price, apply a discount, remove an item, add another item etc.), the Checkout button reappears until it is clicked again.