Regardless of where you are located, we will charge sales tax if the customer's address on the packaging is located in a state where we are registered.
The location of you as the merchant does not play a role in whether or not SPOD charges sales tax on the transaction.
If you’re not located in the USA but are selling to customers in the USA, then you may or may not be liable to charge your customers' sales tax. We highly recommend talking to a tax advisor. You should check carefully whether you need to charge sales tax before making a decision.
For some more information on the topic, we can recommend the tax resources from our partner Avalara: https://www.avalara.com/us/en/learn/guides/frequently-asked-questions-for-getting-started-with-sales-tax-compliance.html