Coupon field in truck: Add a coupon field in truck or naturally show a "Have a markdown code?" connect under the checkout button. Works with Shopify discounts.
Savings before checkout: Allow clients to apply limits before checkout. Show impending reserve funds in truck. Single-tick arrangement accessible for practically all themes.
Discounts stacked in one code: Carter's Smart Deals permit you to stack limits inside one code (markdown % + free transportation, layered limits, % rebate up to $X, and so forth)