I will add that the post office lady did have to spend a few minutes looking up the cost from a huge book. She also seemed unsure as to whether she was correct. "Were you prepared for that [amount]?" she asked, as if seeking confirmation from me that she wasn't wrong. With six people waiting in line behind me I wasn't going to argue a few dollars one way or the other, so I replied "Sure."
After hearing the package contained a photograph and quoting me the cost, she then asked, "Why don't you just email it?" Sigh... Without breaking eye contact I slowly picked up the box and gently shook it. I'm not sure that registed, however.