What is the biblical basis for Christians being instructed to tithe (10%) of their income to the modern day 'church'? I understand the commandment (principle &amp; purpose) of tithing to the Levitical priesthood as defined in OT passages such as Leviticus 27, Numbers 18, etc.

But, my question is now (present day), when there is no temple or clear lineage of the sons of Aaron, what biblical proof texts do Christian (mostly Gentile) pastors use to claim that modern-day believers are commanded to tithe to them (namely, their non-profit organization) as obedience to God?
There are a couple of "proof" texts still used by pastors to command a tithe.


  Bring ye all the tithes into the storehouse, that there may be meat in mine house, and prove me now herewith, saith the LORD of hosts, if I will not open you the windows of heaven, and pour you out a blessing, that there shall not be room enough to receive it.
  Mal. 3:10


Then there's the next question phrased do you want to be the head or the tail based on Deut 28?  Pay your tithes or be the tail (cursed).

There are some groups that claim to be or hint at being of the Levitical priesthood and thus command their followers to tithe.

Lastly, there is the guilt trip.


  But this I say, He which soweth sparingly shall reap also sparingly; and he which soweth bountifully shall reap also bountifully.
  2 Cor. 9:6


To close, we are not under condemnation, but we give cheerfully.