Taxing on Amazon Listings

It is not clear how you are using Amazon, which directly influences when you charge tax and when you do not

Are you using FBA, sending products that Amazon fulfills and ships to customers? If so, you would have to charge sales tax to customers who live anywhere in the United States (as of April 1, 2017, Amazon started charging sales tax to all 50 states). You would have to collect (or eat the taxes, yourself) the exact state, county and municipal taxes for where, specifically, the item is shipping to (there are more than 10,000 different sales tax entities in the U.S.).

If you are "dropshipping" from Amazon, you would have the same scenario UNLESS it is being shipped from a third party vendor, in which case, you would be charging sales tax to items shipped to anywhere that vendor has a sales tax nexus and anywhere YOU have a sales tax nexus.

If you are simply listing your products on Amazon and they ARE NOT shipping them for you, you only have to charge sales tax to shipping addresses where YOU have a physical presence (offices, warehouses, employees, salespeople) - something called a "sales tax nexus".