Depending on what kind of shipping you offer, you or your customer could completely foot the bill, or both of you could. When checking out from your shop, the customer will be prompted with shipping options. If you transfer the cost to them, the shipping cost will be added to the final bill which includes any applicable taxes. If you wanted to offer free shipping, you could either add in an estimated shipping cost to every product you sell, or you could subtract the cost of shipping from the revenue made from the sale itself. The first option allows you to give the appearance of free shipping and will keep more of your sale. The second option lets you sell your products for cheaper, which customers will probably like, but you will end up making even less after you subtract out the cost of shipping.