Proper giving for financially blessed Christians who live in nations that are prosperous is much greater than 10%. It would be impossible to put a number on what exactly is the right percentage for each person. Each individual must seek God's will for their life and give what they feel convicted to give, not what they feel comfortable giving.
We must always remain faithful in our giving. There is no legalistic point at which we can say, "Yes, I have given enough. The rest of my money is mine to use with as I like." All of our money is God's money.
Luke 21:1-4 shares the familiar story of the poor widow who gave sacrificially while the wealthy man gave his much larger gift. Giving out of our abundance is not as blessed as giving sacrificially.
Jesus looked up and saw the rich putting their gifts into the offering box, and he saw a poor widow put in two small copper coins. And he said, “Truly, I tell you, this poor widow has put in more than all of them. For they all contributed out of their abundance, but she out of her poverty put in all she had to live on.” Luke 21:1-4 (ESV).
Let us give till it hurts.