1. A computer-implemented method of billing for printing service costs of a printing device, the printing device comprising a plurality of modules implemented on at least one processor and a storage memory and being configured to print documents comprising at least one page, wherein the method is implemented by the printing device, the method comprising the printing device implemented steps of: 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 for output using the printing device using a calculation module, the usage profile including at least a number of times that the detected object is output over a period of time using the printing device; storing the usage profile of each type of detected object in the memory; and 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 and determined based on at least the stored usage profile, wherein the approximate cost of printing for each page printed by the printing device is determined based on the applied cost function.