Does International Shipping Cost Cover Duties/VATs/Taxes?

All purchase on www.gosun.co are set with the inco-terms as DDU, or delivery duty unpaid. GoSun ships to 100+ international countries, each with specific harmonized tariff codes and duty/VAT/tax rates. We are not able to calculate this additional cost on the front end and thus send packages with duties//VAT/taxes unpaid, which are due to the carrier before delivery.