Moses gave a tenth of all he had willingly, God didn't command or ask him to do that, Hebrew 7:2 refered back to the giving of Abraham without itself asking us to pay it. I believe with the accordance of the new testament to give what I think is right which can be 10%, 15%, 20%, 30, or more. What I posted doesn't contradict giving to God in any way, it just say you can give more than the tenth percent of what you get.