A 5% tariff would barely if at all be felt by anyone but the importer upon whom it is directed.
That made in mexico $12.00 t-shirt you bought last week cost the manufacturer about a buck or less to produce and cost the importer about $2.00 landed here. He sells it to a wholesaler for about $4.00 and the wholesaler sells it to the retailer for $6-7 who then marks it up to 12.00 to get his 40% profit margin.
So how much do you think a 5% increase in any step of bringing this shirt to market means? Nothing is the answer and the importer would most likely eat the increase anyway if his buyer screwed loudly enough.
How bout 25% which is where this would have ended if the Mexicons played hardball.