The import of certain goods, like alcoholic beverages or gasoline, requires a Federal Excise Tax to be paid. The amount of tax is determined by the Internal Revenue Service (IRS), and Customs and Border Protection (CBP) collects it on their behalf.
To determine whether or not additional fees and taxes are required on the goods you are importing, you should contact your port of entry and ask for an import specialist.
You can also learn more about the excise tax here on the IRS site.