Each market decides how its discounts combine. The settings are on the market's Discount Settings tab and apply to every discount in that market. A new market starts with One discount per order, Best for customer, one coupon per order, Automatic discounts with coupons turned on, and Discounts on quantity-priced items turned off.
The Example order on that tab shows which of three sample discounts apply and updates as you change a setting, before you save. On the Discounts tab, How discounts are applied works through an example order for each type.
One discount or several
With One discount per order, a single discount applies. Tringify compares every eligible automatic discount and every code the customer entered, and picks one by your ranking. With Allow stacking, every eligible automatic discount applies, together with coupon codes up to your Coupons per order limit.
Ranking discounts
Best for customer ranks discounts by how much each one saves on its own. Manual priority ranks them by the priority number on each discount, lowest first. The ranking picks the discount when only one can apply, chooses which codes fill the coupon limit, and decides which offer keeps items that two offers both need. Discounts are ranked one by one, so the ranking doesn't search every combination for the largest total. When two discounts rank equally, automatic discounts come before codes.
Coupons and automatic discounts
Coupons per order caps how many codes can apply to one order; automatic discounts don't count toward it. The highest value you can set is a platform limit that checkout enforces too. Automatic discounts with coupons decides what happens when both qualify: on, they apply together; off, codes don't apply while an automatic discount applies to the order. Neither setting changes anything when only one discount applies per order.
Offers that use specific items
Buy X Get Y, bundle and gift offers use specific items in the cart: Buy X Get Y uses both the bought and the reward items, a bundle uses every item in its set, and a gift uses the gift item once it's in the cart. Two of these offers can't use the same items. The higher-ranked offer keeps them, and an offer that can't get every item it needs doesn't apply at all; it isn't reduced to fewer sets. Other discounts still apply to the value left on those items.
Order of application
Discounts apply in three steps: Buy X Get Y, bundle and gift offers first; then discounts on selected products, collections or categories; then order-wide discounts. Within a step, discounts follow your ranking. Each discount uses the amount left after the earlier ones. For example, on a 100 order with Manual priority and the 5 off ranked first, a 10% discount saves 9.50, not 10. Minimum spend, minimum quantity and tiers are checked against the cart before any discount, not against the reduced amount.
Quantity-priced products
Products with quantity pricing already have a volume price, so by default they are left out of every discount in the market: they get no discount and don't count toward a discount's minimum spend, minimum quantity or tier. Turn on Discounts on quantity-priced items to let discounts apply to them as well, on top of their quantity price. A manual order-level discount you add to an order covers quantity-priced items either way, but not Gift Card products; see Create an order.
When you change these settings
New settings apply the next time a cart or checkout is priced. Orders already placed keep the discounts they were placed with.