Bonus To House Members From My Wins

Hi all. Greetings from Perth Australia

In House Chat we get coins from other players when they get a big win, so I know they must get something from my wins too, athough I'm not a really big winner. 

Now I'm curious - how do the boffins wrk out what amounts to award? 10% of winnings? They must have some sort of formula.

Any ideas?