I need help in numerical inputting

In my masked textbox coding, I wrote "#,###,###.##" format string for my application where it is an atm-similar deposit/transfer app.

I had like my application to appear in the manner below and so, there's the scenario I wanted.

Example, users is going to transfer an amount of 543.12 and I had like the inputting to appear as like this : (I write it as a 'step-by-step basis')
1) _,___,___._5
2) _,___,___.54
3) _,___,__5.43
4) _,___,_54.31
5) _,___,543.12

Instead of the numbers appearing via the front or that the user have to move the cursor to enter the fixed amount, is it possible to for the numbers to appear at the back?