Yes, we do combine the shipping as much as we possibly can. If you use a laptop or a desktop computer, you can add all the items to your cart, and then from your cart screen, hit the request total tab, and then commit to buy. After you commit to buy, the items will show up as sold, but not paid for on our end, and we can then send you a new combined invoice.
However, if you are using a mobile device, the request total tab is usually not supported and probably will not be on your cart screen. In that case, the only thing I know to do is to send a refund for the excess shipping after all the items are bought and paid for.