Ring up the worst cart before your customers do.

I run paid social budgets in Toronto, and every Black Friday someone finds a promo stacking in a way nobody planned. Big brands have teams to catch that. Small Ontario shops usually don't, like The Bakers Bar in Gravenhurst, a friend's store selling bath bombs, soaps, organic creams and infused cupcakes. In Canada, where shipping isn't cheap, one over-stacked order with free shipping can wipe out a sale's margin. Shopify keeps each discount's settings on its own page; this puts every combination on one screen.

Note: this version has been modified as a portfolio piece for my Shopify APM application.

Discounts stack only when each is set to combine with the other's class (product, order, shipping). Product discounts apply first, then order discounts on the reduced subtotal, then shipping. One shipping discount per order; two product discounts never stack on one item (the bigger wins); up to 5 codes. Taxes, payment fees, Buy X Get Y and app discounts aren't included. Minimums are checked after product discounts.