Adobe Acrobat Fillable Form Formatting

I am looking for a Custom Format Script and/or a Custom Keystroke Script that can be used in an Adobe Fillable Form to display an input value as #.###%. (For example, if a user inputs 4.25, I would like this field to be displayed as 4.250%.) The correct answer is NOT to use the Percentage format instead of the Custom Format. The user is inputting this value in an Input Mask and the value from the Input Mask is used in multiple places within the document. The problem with using the Percentage format is that it does not default to a null value, so if the field in the Input Mask is left blank, it defaults to 0.000% and this appears in the linked fields throughout the document. I am using 'if ([login to view URL]) [login to view URL] += "%";' as a Custom Keystroke Script to add the percentage sign to the value in the Input Mask, so I just need some assistance with converting the number so that it has three decimal places. I will pay 10 USD for a solution, but I need this in the next two hours. (By 4:30pm Eastern Standard Time)