The border agency in the country where you sent your parcel to is responsible for calculating all duty and taxes for your shipment. We have no input in the process, and the money is paid by the receiver to the border agency.
Each country has its own regulations and charges, search for the country you are shipping to for more information.
The price you pay is relative to the value of the goods that you are importing.
Note: if you are sending gifts or personal effects, you may not have to pay import tax or duty. This is dependent upon the regulations of each specific country.