I think the easiest and quickest way to get the result you want is to create "Fixed $ off" discount.
To properly handle cases where customers order more than 4 doses, we need to create a separate discount rule for each quantity range / scenario.
4 DOZENS
- discount value: $12.00
- Applies to Specific item/group
- Add item and change the quantity to "4" (assuming you have an item called dozen cookies/cupcakes)
5 DOZENS
- discount value: $15.00
- Applies to Specific item/group
- change the quantity to "5"
6 DOZENS
- discount value: $18.00
- Applies to Specific item/group
- change the quantity to "6"
7 DOZENS
- discount value: $21.00
- Applies to Specific item/group
- change the quantity to "7"
8 DOZENS
- discount value: $24.00
- Applies to Specific item/group
- change the quantity to "8"
9 DOZENS
- discount value: $27.00
- Applies to Specific item/group
- change the quantity to "9"
10 DOZENS = 5 DOZENS + 5 DOZENS
11 DOZENS = 5 + 6
12 DOZENS = 6 + 6
13 DOZENS = 7 + 6
... and so on
Another approach is to set up a "BOGO" discount. Instead of framing it as "Buy 4 dozens and get $3 off each dozen" , reword it to something like: "Buy 2 dozens, get 2 dozens for $12 off!" This keeps the exact same economics (total $12 savings on 4 dozens) but positions it as "buy 2, get 2 at a big discount"
