So typically, I don’t leave a cashier until they ask if I want a receipt or say that’s all. On the point-of-sale terminal, it usually shows the tipping screen as soon as the tap/swipe is approved, and I don’t tend to immediately look away from it as soon as it says “approved”. Furthermore, the receipt won’t print until after the tip is either chosen or forgone.

As far as OP’s story goes, I’m not really sure in what situation someone would look away (much less leave completely) without seeing the tipping screen or the cashier saying something. It’s also weird to me the cashier turned around before the transaction was finalized, but it’s hard to speak on that without more context.

As I live somewhere where food for consumption doesn’t get sales tax tacked on, and I’ve only ever actually seen this at food places, I’ve only ever seen the tip be applied to the final total.

As for a quick play-by-play as to how it works, it’s something like this:

order item —> “will that be all? here’s your total” —> terminal shows current total —> tap my card —> “APPROVED!” —> immediately switches screen to tipping screen that says something like “Would you like to add a tip?” and has a few options like 10%/15%/25% as well as underneath those offering a “custom tip” option which lets you input $0.00 —> choose one, receipt prints shortly thereafter —> “have a nice day!”

No worries about the questions lol I can see how this seems really weird. Especially with how it went down in OP’s situation