Splitting a bill is three different jobs, not one button
Equal ways, by item, or by amount — each share with its own way of paying. What a till needs before "split" stops meaning "get a calculator".
Ask a till salesperson if their product splits bills and the answer is always yes. Ask the person who closed Saturday night and you hear about the calculator kept next to the terminal. The gap is that "split" is three different requests wearing one word.
The three splits
- Equal ways. Four people, quarter each. The only part most tills genuinely do.
- By item. She had the ribs, he had a lemonade. The till has the lines already; the split screen has to let you deal them out.
- By amount. "Put twenty on this card and I will get the rest." No relation to the lines at all.
A real table is usually a mixture — two paying equally, one taking their own items, somebody's parent throwing in a fixed twenty — so the three have to compose, not sit on separate screens.
Each share pays its own way
The half of this that gets missed: every share needs its own tender. One person pays cash, two tap cards, one has a voucher. A split that assumes one payment method has only moved the arithmetic, not solved it. (On our till, card means recorded card — the amount is typed at your external terminal and recorded against the share. We do not process cards, and say so plainly.)
The two details that decide whether it works
Pennies have to land somewhere deliberate. £50.00 across three people is not £16.6667. The till decides — first share carries the odd penny — and shows it, so three shares always sum to the bill to the penny. "Roughly a third" is how a drawer ends the night wrong.
A part-paid bill must survive. Two shares settled, one person stepped out — the order has to hold that state, visibly, and be finishable later. A split that must complete in one breath will be abandoned the first time service interrupts it, and the workaround becomes the calculator again.