Output Capacitor Value
My values are: Io= 380, D= .388, Fs= 1200


This doesn't seem right. You're saying that Iout = 380A, Duty Cycle = 38.8% and Fs = 1200Hz? That's what those values mean plugged into the equation.

Also, the output voltage is something that you spec out as a designer. This depends on how tight you want the converter to regulate. You could choose a ripple of say 1%. This would mean:

DeltaVout = 0.01 x Vout

Ror a 5V output you'd use 50mV (0.05) for the equation.