Currently Savant does not include the cost of tariffs with the Unit Cost they provide through Vendor Partner Pricing. You will likely want to adjust the Unit Cost to account for these tariffs so you have a more accurate margin in Projects and an accurate price on Purchase Orders.
If the tariffs are a percentage of the Unit Cost for some/all of the products, Price Rules are an option to adjust the Unit Cost. For example, let's say the tariff value will add 6% to the Unit Cost. Set up a Price as shown below where the Unit Cost = Unit Cost * 1.06.
You can create as many Price Rules as needed. If some of the products have a different tariff amount than others, use any of the filters in SI and then apply the Price Rules to the selected Products.
If you feel more comfortable working in Excel, you can always export your products (filtered or all) to a CSV file, update the Unit Cost with math and whatnot, then import the CSV file back into SI to update your Unit Cost to include the cost of tariffs.