Yes, don't hand it to a clerk. Put it in a postal collection box. They will hardly ever bother to make a fuss (like bill the receiver for Priority Mail, or parcel rate).

Here are the Physical Standards if you are interested -- good to bookmark:
http://pe.usps.com/text/dmm300/101.htm#wp1039555+

This is good to bookmark too (lots of prices). http://pe.usps.gov/text/dmm300/Notice123.htm At the bottom is this chart:

Robert
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John Wayne (center) and Ben Johnson (2nd right) in "The Train Robbers" (1973).
http://www.antiquegamblingchips.com/StillsA_TopMaleStars.htm