An extra fee is showing up on more shopping bills lately, and it carries a not-so-subtle message: These tariffs weren’t our idea. From bathroom-fixture makers to toy shops, companies are starting to tack tariff surcharges onto invoices as a separate line item. Some are a $5 flat fee, while others represent as much as 40% of the subtotal. The tactic is a way to pass on at least some tariff costs to consumers—especially on Chinese-made goods, with levies totaling 145% since January—while passing the buck to President Trump. “We think transparency is the way to go here, and I am...