Three-for-two applies at the till even with the line down.
The rules live in two places at once, on the server and inside the till, written the same way. That way the till applies the promotion even with the internet down, and on sync the server recalculates it and its result stands: nobody gives away too much at the counter and nobody loses a discount because the line failed.
The rules live in two places at once: on the server and inside the till, written the same way. So the till applies the promotion even if the internet is down, and on sync the server recomputes it and its answer is the one that counts.
Nobody can give away more from the counter, and nobody loses a discount because the line dropped.
You do not have to switch everything on. Tell us how you work and we will tell you where to start. ATAZEL is in testing: write to [email protected].