You can incentivize your customers to make bigger purchases by offering volume discounts via the Product variants feature.
Step 1
In the Editor, go to the Webshop tab. In the menu on the left, click on Products, then either add a new product or select the product you want to edit.
Step 2
Name the product something to the effect of "4 pens for $4" to highlight the discount being offered.
Step 3
In the Edit product dialog, under Product variants, click on the Add product variant button.
Step 4
Add product variants for different quantities of the product, as shown in the example below, and click on Save.
Step 5
Enter prices for each quantity, and click on Save.