In fact, God said that if they did not give it then He would charge them interest. It would have been cheaper to borrow from the bank than to take God's rightful firstfruits. We are to give out of our income. We, too, honour God by our giving. If you do this, you will have a pretty miserable year and will have to work it out for yourself when things don't go right.
New wine is a figure of prosperity and affluence in the Bible.
So God's promise is available to you and God's principle is for you to take the first step and give Him a percentage of your income. Give it in faith out of what you have. Now it is on God's shoulders to fulfil His part of the principle and guide you in a way that will fill your barns with plenty. A similar statement is given in Malachi, chapter 3. God says to test Him out, and you do it by giving.