PTO is not just built on the Lacerte chassis but actually uses the nuts and bolts and the same engine.  However, it does not come with all the bells and whistles for the price, so you will need to live with the lack of features and flexibility.

PTO pretty much runs the same calculations that Lacerte does, although it may not provide as many options.  Federal interest calculation, unfortunately, is one where you will need to prepare the computation offline and plug it in.

TBH, I can't understand why Intuit would leave out such a simple logic for calculations than can easily be run on a spreadsheet, especially since it does compute state interest charges so long as you enter the interest rates and input 1 for automatic calculation.