If you have ever wired up a "calculator widget" in a checkout flow, expense module, or hospitality backend, you have probably discovered that the boring question — do we tip on the pre-tax subtotal, the post-tax total, or something in between? — is not boring at all. It is a tiny rules engine w...
Source: [Dev.to](https://dev.to/lizely/tipping-on-a-pre-tax-vs-post-tax-base-a-reference-sheet-for-engineers-who-build-the-math-57ad)