I think everyone is afraid to answer this one because as on now it depends on what P.O. you go to an which clerk in that P.O. The best you can do is pack up several packages as you discribe and take them to the P.O. and have your favorite clerk weigh each one for you. After the correct postage has been determined,then only go to that post office and use that clerk each time because it changes with location and clerks!