In Brazil, private couriers like FedEx, UPS and DHL charge the recipient/customer for a special fee which includes taxes + shipping. If the government taxes the product above the fee, the courier will charge the customer at delivery for the difference (Amazon, for instance, covers this cost if that happens). That may be what FedEx is trying to pull in the US for you.
This system is adopted to avoid the customs line, as couriers operate by plane and on a speed dial, and the federal payment system (done through govt./customs channels), which is morose. The fee itself protects the courier in case of overtaxing and of the recipient not paying his taxes.
The result is the federal import tax + state tax for the circulation of goods and services (ICMS) + courier's service fee, which all amounts to about 110-120% of the original product.