A lot of this depends on the Postal Branch that you go to....I will NOT go to the one that my mail comes out of, the people are rude and just snap at customers. I'll never forget the time I paid with a $5 for something and received my change in stamps, because she was nearly out of change. What can you do with a bunch of 5 cent and 10cent stamps???
I just wanted to comment about turning the box inside out...can't do it anymore...they have writing all over the inside of the box, too.
I keep 2 of each size that I would use here at all times for my shipping needs. When I use one, I get another. This system has worked for a few years......