It doesn't affect a lot of US consumers, but it will affect a lot of US retailers.
Let's say after 2019-01-01 I want to purchase a $500 gadget that's being hit with the 25% tariff. I can either:
1. Buy it from Amazon or a local retailer and pay $500 x 1.25 x 1.085 (state and local sales tax) = $678
2. Buy it online from AliExpress/BangGood and pay $500 + shipping