In my business we split it "evenly" with weight given to how many hours each person worked on each project. You could think of it like a variable hourly wage based on the profit of the business as a whole. But that's just one model that works for us as a small firm, there are other ways to structure it. Again, I recommend reading about Mondragon's policies for another example, though I can't say I agree with everything they do, but that's up to them not me.
> And who decides each year/quarter what portion of the profits go to employers ...
I'm assuming "employers" was meant to be "workers", as there is no longer a separation between employee and employer. Everyone is equal.
Ideally this would be decided by all the employees through consensus-based meetings, with some discussion about what is necessary and what is not. That's not to say there can't be financial experts involved giving more knowledgeable opinions, but the decision must be everyone's.
People are more incentivized to let some profits stay in the company if the company is theirs. It's not much different from how the capitalist feels about "the company's money". The co-op company growing stronger is directly beneficial to each and every individual worker. If I personally work extra hard, I directly gain more money in my paycheck. That does not happen with a capitalist company, where working harder benefits one or a few shareholders who have nothing to do with the work being done.
