Payment Fee = + - 3.99 (payment processor charges)
Tax Clearance Fee (once off) = 3.00 (last time I checked)
Payout Fee = + - 2.84 (payment processor charges)
You should be able to withdraw about $74.17
You can just request a payout. Itch.io will adjust the balance before paying it out (i.e. fixing up the tax withholding).
Once you receive a payout there is a detailed calculation under Payouts showing how the payout amount was calculated.