"You shall bring the very first of the first fruits of your soil into the house of the LORD your God." Exodus 34:26 This would suggest bypassing paying anyone (including Uncle Sam) else first. And always remember, the Hebrew premise of a 10% tithe was considered only a starting point - a minimum.
Also keep in mind Mal 3 - it is the only place in scripture where God calls us to test him. He tells us if we bring the whole tithe (otherwise we rob God), He will throw open the windows of blessing upon you. And, He never lies.