One thing that is for sure is that as believers we are called to return (not give since you don't give back to someone something that they already own) a portion of what is God's back to him (assuming you believe that everything you have was provided to you by God).
A Couple Interesting Stats:
The average church-goer gives only 2-3% of their annual income to the local church.
The average church reports only 8-12% of their attendees actually fully tithe.
There is an increase in giving in our nation, but not to the church... it is going to other organizations.
What would the church look like if everyone tithed.
FIRST... the church would never have to mention it because it would be taken care of.
SECOND... the needs of the congregants could be met and the church would be fully equipped.
THIRD... we would not need government to do the things the church was supposed to be doing.
There is so much more to this topic but I know this... I have the umbrella of God's blessing over me in this area because I do it and the cool thing is... I LOVE IT! I love actually giving to our church my full tithe. It feels GREAT!