You need to make sure you fully understand the tax and selling laws of the country you intend to sell in.
In the US, buyers may have to pay a sales tax, but this isn’t the case for every state in America. Make sure you fully understand the tax laws in the countries you intend to sell to and that your customers are aware of where your core business is based.
Your local tax authority will be able to offer specific advice. If you don’t give the option to let customers pay for VAT/duties when ordering, they could be charged at the doorstep and will also pay a steep processing fee with the carrier, meaning they’ll unlikely shop with you again.