Call a Calculator from a fillable form

I have a form that is used to report the gross sales of prepared foods to a local government. There is a local tax of 7% on those sales and it is paid by the purchaser. The restaurant them remits those collections to the City. If the payment and reporting is done timely, the current form is very adequate. However, if the reporting and remittance as late, there is a penalty and Interest that is applicable. The variables for calculating the interest are the due date of the reporting, the actual payment date.

I would like to have a button on the form that will allow the merchant to calculate the interest due if the merchant knows that it will be late filing and remitting. The merchant, after calculating the interest enters to total calculated on the fillable form and closes the calculator.

Is that possible to do with LiveCycle ES2?

Thanks!!