For United States buyers, the Good news, there will be no tax at all. Sweet
For EU country buyers, the tax is already included in the shipping cost.
For other countries (Canada, Peru, UK and etc.) We always mark the value around 15-50USD for each package to lower the chance for you to get taxed for importing goods.
However, we can't ensure that the local customs will not have questions about the value of the package. You can contact us about the issue, we will try to help you. But if the customs eventually needs to pay additional tax, the buyer should bear the relevant charge.