Agree that it depends upon who is at the counter. I have one guy at my PO who really "works to rule"! He once charged me extra on some manila envelopes with those metal closures, saying there is an up-charge for those ...from then on, I always pull the metal closures off and just tape the envelopes shut!
It's a shame that postage is going up again. I have pretty much stopped all e-baying because people will make a fuss about shipping cost, but it's truly not the seller's fault. The power-sellers can give shipping discounts and still make some money...we average sellers cannot. It's just a fact.