Nino Gaggi apparently always suspected that Roy DeMeo was making more than he was letting on (he was).
Everyone in the mob lie's about how much their really making.

I dont know what the rules are for a Capo wether he has to kick up a set amount each week/month to the Underboss who takes his share before passing it to the boss?

The trouble is with giving a set amount (for a soldier) lets say he muscles in on a thriving nightclub in the middle of Manhattan and he's pocketing $5000 a week (just for a figure).
He gives $2500 of that to his capo who then expects $2500 each week.
Suddenly the nightclubs customers find a better place to party the night away - takings start to tumble, and the soldier is only getting $3000.
The soldier has to chose wether to give the capo $2500 and only pocket $500 himself or threaten the club and demand the $5000 he initially got but if he does that it wont belong before the club goes out of buisness and then his meal ticket will be gone!

I think some captains were more understandable than others