Hi there Larkins,
Please read our blog post on importing into the USA Link hidden: Login to view.
Exactly what tariffs you have to pay depend on what you are importing. This can be difficult to work out, so we recommend contacting a customs broker to help you out the first time you import.
However, there are a couple of great links in the blog post above that should give you an indication of what you can expect to pay for your items.
All the best