Documentation Support > Cart > Shipping
The ZAP shopping cart uses a standard shipping formula, based on what I personally use. If you can do a bit of javascript programming, you can customize it however you wish.
By default, it looks for a "usorder" field. If true, it charges a minimum shipping of $4, 15%, and FREE over $100. If not, it charges minimum $10, 20%, and no free shipping.
You can also configure the calculate function, to include for example sales tax or some other value. By editing these values you have a good bit of flexibility in how ZAPcart works.