How much will I now pay in duties to ship a stylus from Japan?

If you are purchasing on Ebay, they have a SpeedPak option where they calculate the shipping and fees up front and add it to the cost of goods. You just pay whatever the total invoice is when completing your order and wait for it to be delivered. Tracking is included, though I'm not sure if there is a total value limit on the item you're purchasing.

A tariff is not paid by the seller in the country of origin, unless the seller chooses to reduce the cost of the item so as to absorb the tariff. The tariff is paid by the buyer in the destination country. By definition. “Duty” = tariff in this case.

FedEx Invoice billed: 

Disbursement Fee ......... $4.50

Customs Duty .................$16.35 (on net cost of cartridge Y15,600 ($109.) (Japan is 15%)

as I said, there is no duty collected on the various fees and shipping costs.

https://www.cbp.gov/travel/international-visitors/know-before-you-visit/customs-duty-information

A lot of sellers are equally confused. But the buyer pays it. This is a form of tax by the US government and it is not the responsibility of a Japanese proprietor to figure out, and to pay, US taxes. Similarly, it is not the responsibility of shipping agents or companies. Some have opted to not ship any US shipments at all, in response to the tariffs, depending on the country. but it seems to be settling into a pattern of an added cost forwarded onto the buyer by the shipper. That is what happened to me with the shipment from Poland and I owed money to FedEx for it.

for a purchase of mine from Singapore (Laiv Harmony equipment) The inventory was already in the US in a distribution warehouse before the tires were implemented, so I did not need to pay for it. Depending on the company you’re dealing with that may be also there to work for your advantage.

Sigh.  Speech to text…  I hope you are all good at deciphering what people “really mean” in this modern age.