Per Grabr’s terms, travelers are responsible for customs duties and fees. For this reason, we recommend you look up applicable custom fees before making a delivery offer.
You can search via World Duty Free and sort by country (head to the search bar at the top left of the site) before making a delivery offer. This way, you can include this amount in your traveler fee.
Please note that neither shoppers nor Grabr carries responsibility for violations of customs limits conducted by travelers.