I don't know if you can get NumberFormatter to do the job or not.
If not, you can pad the strings to a known length. I made a function right() for rightJustify that pads or truncates to a specified length and lets you specify the pad character or
string:
formatted = StringUtil.right( input, 10, " " );
For one-off use, you might make a method that does this:
return (" " + input).substring( input.length() );