Just to be clear, I don't thing CD Japan is adding monies for tariffs-it is the job of the US Customs office to impose that. Yes, CD Japan's shipping charges have gone up because, I think, the shipping companies, e.g., DHL, FEDEX, are charging more money in anticipation of additional hassles relating to the imposition of a tariff, whether in fact a tariff is imposed.
My cost for shipping for the 4 items in my latest order (my smallest order in years, perhaps ever) was essentially the same cost for my previous order of 7 cds.
And, the "customs clearance fee" was a set price, 1300 yen, whether I bought 1 or 4 cds, which influenced my decision to buy more than 1 item this time.