How do I cancel a POS sale, and when does the system block it?

A cashier picked the wrong item or quantity and completed the sale. Cancelling reverses everything at once, but its window is deliberately narrow.

Steps

1. Press Recent in the POS bar to see the latest sales, or open Sales → POS Invoices.
2. Open the sale and press Cancel.
3. Confirm: "Are you sure? This will reverse the invoice, its receipt, stock and journal entries."

What gets reversed

• Stock — the quantities go back into the terminal's warehouse.
• The journal entry — the invoice's entry is reversed.
• The receipts — all of them are deleted, including every leg of a split payment, not just the first.
• The sale's status — becomes cancelled.

When the system blocks you

1. The shift is closed. The message: "Cannot cancel this transaction because its shift has already been closed." That shift's cash has been counted and reconciled, so it cannot change retroactively. Cancel before closing the shift — that is the window.
2. The invoice has a return. The return already gave part of the goods back; cancelling afterwards would credit the quantity a second time and inflate stock. Delete the return first.
3. You lack the permission. Cancelling a POS sale is a separate permission from cancelling ordinary invoices, usually given to a supervisor rather than a cashier.
4. It was already cancelled by a simultaneous request; the system prevents a double reversal.

Notes

• A POS invoice can never be edited, neither at the till nor from the invoices list. Cancel and re-ring is the way — image 1.
• Once the shift is closed, the only route left is a sales return with a refund.
• Review the sales before closing the shift; two minutes there saves a return and an extra piece of paper.
• Cancellation is written to the activity log with who did it and when.