Actually, this is a modern thing. In the old German language (pre-1800) the numbers were spelled in the correct order in the areas where Hochdeutsch was spoken, with the single digit being at the end.
Also some early books from the era directly after the 30 jaehrige Krieg still use the different way of spelling numbers (e.g. from Eva Hartner comes to mind).
Einhundert-Zwanzig-und-Eins is still a number everybody understands, and it is also accepted in written form on bank transfer checks.
So I'd say just go ahead and use it this way :) the more people use this way of spelling numbers, the more likely it is that the language will adapt and change (back).
Also some early books from the era directly after the 30 jaehrige Krieg still use the different way of spelling numbers (e.g. from Eva Hartner comes to mind).
Einhundert-Zwanzig-und-Eins is still a number everybody understands, and it is also accepted in written form on bank transfer checks.
So I'd say just go ahead and use it this way :) the more people use this way of spelling numbers, the more likely it is that the language will adapt and change (back).