1. A method of billing for printing service costs of a printing device, the printing device being configured to print documents comprising at least one page, the method comprising: examining content of each page in the documents using an examination module, the examining comprising: (i) detecting at least one object in the page; (ii) determining a type of the at least one detected object within the page, and (iii) determining an approximate area of coverage of a detected object within the at least one object in the page; calculating a usage profile of each type of detected object using a calculation module; storing the usage profile of each type of detected object in a memory; applying a cost function to approximate a cost of printing the page using the at least one detected object, the determined approximate area of coverage of the at least one detected object, and a weight value, the weight value being associated with the type of the at least one detected object, wherein the approximate cost of printing for each page printed by the printing device is determined.