In my personal case, the $36 going for SXM departure fee/tax is the biggest add-on followed by the US transportation tax. A total of over $129 in taxes/fees.

Taxes, Fees and Charges
United States - Immigration and Naturalization Fee(Immigration User Fee) (XY) $7.00 USD
Sint Maarten - Passenger Screening Fee (FG) $10.91 USD
Sint Maarten - Airport Departure Tax (SXM) (FH) $36.00 USD
United States - September 11th Security Fee(Passenger Civil Aviation Security Service Fee) (AY) $11.20 USD
United States - Animal and Plant Health Inspection Service Fee (APHIS User Fee - Passengers (XA) $3.96 USD
United States - Custom User Fee (YC) $5.50 USD
Sint Maarten - Airport Improvement Fee (IW) $5.50 USD
United States - Passenger Facility Charge (XF) $13.50 USD
United States - Transportation Tax (US) $35.60 USD