This setting is Cart & NetSuite specific and may or may not be available to on your Cart / NetSuite Platform.
Step 1: Open eCC and "go to File >> Configure Store >> Discounts screen."
Step 2: Choose your discount item from NetSuite and click on 'Save'.
If the Item is not visible / not created in NetSuite, follow the steps below:
Step 1: Open the 'Item list' in NetSuite and create a new item of type 'Discount'.
Step 2: Click the 'refresh' icon in the eCC's Discount configuration area to bring in the new details from NetSuite and then choose your 'discount item' from NetSuite and click on 'Save'.