How tax rate is determined for products marked taxable in 2.0

When you mark a product taxable, the tax rate that is applied is determined automatically based on your customer's shipping address. If your customer has not specified a shipping address in their account, the tax rate is based on the address you have specified on your Settings page Business info tab. Note that if your customer has specified a billing address it is never used.

If you have applied a global tax override on the Sales tax tab of your Payment page, that tax rate is applied to all products marked taxable.