How to add shipping percentage at checkout

[andreadanychuk]

So I get charged shipping when I order my product!  I need to add a percentage to my amounts for shipping that I have been charged already!  Can someone help with this please.

[JustinC]

I'm a bit confused. In this case, are you the buyer purchasing your own product or are you trying to add shipping to your customer's purchases? 

@andreadanychuk