There's no denomination or sect that actually tithes 10% on average. There was a freakonomics episode about it. There was as researcher who found that certain donominations tithe more or less but none reached 10%.
I currently live in Utah which, for those who don't know, is predominately of Mormon faith. While those rates aren't published for some pretty clear reasons the overwhelming majority of individuals I've spoken to within the industry tithe at or above 10%. Granted this is the tech industry so middle class and above is common but it is pretty much a requirement to be an active member of the church.
