You have created an Item-Based Promotion and when you apply it to your transaction, it takes away the discount only once per line item.
The Item-Based Promotion you have created is to give a discount of $5 off for Item A. When Item A is entered in the transaction, but the quantity is more than 1, it will only deduct $5 once. We are expecting that for every Item A entered in the Transaction, it will take $5 off (Quantity is 2 for Item A, total discount should be $10). The discount is only $5 off regardless how many is the quantity of the item entered in the transaction.
We need to create tired Promotion. It is possible to add up to 10 Tiers in Item Based Tiered Promotions.
To do this, follow these steps:
1. On the create new Promotion page, mark Create Tiers.
2. On the Eligibility tab > Order subtab > Add Order Criteria, select Select Items.
3. In the Item field, select the Item to add discount.
4. Define Tier 1 as 1 unit then click Add Tier.
5. Define Tier 2 as 2 units then click Add Tier.
6. Continue to desired number of Tiers - up to 10
7. Click Save.
8. On the Discount tab > Add Item Discount field, select Select Items and select the same Item as in Step 3.
9. In the Promotional Offer field, select Currency.
10. Add Discount per each Tier - e.g. $5 for Tier 1, $10 for Tier 2.
11. Click Save.
12. Click Save again to save the Promotion record.