I believe that paying tithing to God is similar to the "Word of Wisdom", a principle with a promise. I think that the ultimate blessing we receive from paying tithing is simply being able to gain a testimony of the first law of heaven, which is the law of obedience and sacrifice.
There are many wonderful stories of financial success attributed to the fact that the individuals involved are full tithe payers. These stories can be very faith promoting but there are many instances of people who pay a full and honest tithe and do not receive monetary gain in return.
That is not the promise, the promise is: (Malachi 3:10) "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."
When the "windows of heaven" open I feel that the blessing is simply a more increased power to receive light, just as an open window lets in the sunlight. Obedience to the commandment of tithing or any commandment for that matter, allows one to "prove" the Lord to see if His word is sure.
Understanding law helps: D&C 130:20 "There is a law, irrevocably decreed in heaven before the foundations of this world, upon which all blessings are predicated— 21 And when we obtain any blessing from God, it is by obedience to that law upon which it is predicated."
Paying tithing allows one to call upon the blessing attached to obedience to that law, of added light and knowledge. The temple is, among other ways, one of those places we are permitted to go to receive that added light and knowledge; it is allowed because of the obedience to the laws that predicated it, one being tithing.
In the Christian society there is often a debate over who we are to pay our tithes and offerings to.
I remember an old joke that went something like:Lord, I will throw my money up into the air and whatever you need you keep, and whatever you don't need, let it fall to the ground and I will keep.
Similar to this bit of humor, when we decide the conditions of the law instead of the Lord and choose who we want to pay our tithes and offerings to, we are essentially doing the same thing as the person in the joke.
One of the earliest recorded instances of tithes being offered is in the scriptures, in the book of Genesis. It is when Abraham paid tithes, after his return from his conquest in battle, while delivering Lot from his enemies.
In Genesis 14:20 it explains what Abraham does next with his increase, “And blessed be the most high God, which hath delivered thine enemies into thy hand. And he gave him tithes of all.” It is more interesting to note to whom he paid the tithes. In Genesis 14:18 we read, “And Melchizedek king of Salem brought forth bread and wine: and he was the priest of the most high God.”
He paid tithes to Melchizedek because he was the rightful priesthood holder being the priest of the "most high God", or in other words, one having authority to act in God's name. I think the matter of debate is not one of "if the Lord requires tithing" but more the matter of who is the rightful representative of the Lord, holding the office of High Priest for one to pay their tithing to. For me, that holder is the Bishop of my ward, the High Priest of the Aaronic Priesthood, and Melchizedek Priesthood holder of the most high God.
Finally, God does not need our money for himself, but we need to learn to become obedient and learn to sacrifice for ourselves so that by "law" he can bless us with the further light and knowledge that is required to come to truly KNOW Him. He, as a loving Father is leaving that decision in our hands, and we must learn to open our hands and give, and make it as an offering in righteousness to know HIM.