If I had to guess: this might refer to what is called "keeping two sets of books." This is usually done to avoid paying taxes, although it could also be done to hide more nefarious practices. One book, for the revenue service shows the fake amounts with all taxes paid correctly, and the other, for your personal use, shows the real amounts. "Front numbers" might refer to the fake accounts.
Do you think that could be it? Steve's father only shows him the fake books, hoping that his son will grow up to be an honest businessman?