If Amazon collects sales tax from customers on your behalf, setting a tax code based on the type of product will ensure the customer is being charged the correct amount of tax for the item.
The code can be entered for items while on the Item Listing Details page as you're adding the items to batches.
To add a tax code, click the Tax Code field and select the appropriate code.
You can also set the tax code to default to the last code used in your Remember Last Entry Settings.
Additional information about Product Tax Codes can be found in Seller Central: