G.B.R: Fast Response Group/G.B.R.: Special Commando Unit how to grind money.

I don't think I'll ever be able to bring myself to suffer through recording this entire game, so to any brave souls or the curious, you can end missions prematurely to grind money from kills.
For anyone who hasn't played this game, you permantently lose money if you quit out of a mission (Any money spent on mandatory-extra ammo and teammates), so this is really the only way to realistically avoid getting soft-locked.