Create a button that would take you to the main/home screen and possibly a second button for the main area in which the user is navigating (lets say the area sales, or finance or manufacturing). This will help the user not getting lost among the areas that the user has been navigating around. I think the customer would try most of the times just to hit the "back button" as many times as it need to get return to the main menu, but this can be confusing as users browse from one area to another.