Added Store › Discounts. A discount gives a percentage off, an amount off, free shipping, or buy X get Y, and applies to the whole order, chosen products or chosen collections. Buyers enter a discount code in their cart; an automatic discount applies to every cart it fits.
Each discount can have a minimum amount or number of items, start and end dates, a total use limit, a limit per customer email, and a choice of whether it combines with other discounts.
Stripe's payment page and receipt show the discount, and each order keeps the discount it was charged with. A checkout that is not paid gives its use back, so an abandoned checkout does not use up a limited code. Accounting records Store discounts under Refunds and discounts.