When you first open up iLeaseMyCar Pro you need to configure your sales tax settings for both the Lease and Loan calculators.  To do this, press the info button in the lower right hand corner.  You'll need to do this for both "iLease" and "iBuy".  They are completely separate so the setup has to be done in both places.

Follow these Steps to setup and use iLeaseMyCar Pro 4.0 - iBuy