If you get any argument from your post office, tell them to look
in the "Domestic Mail Manual", Section 713.1.1(e), "Media Mail".
This section states:

  "Sound recordings, including incidental announcements of recordings
  and guides or scripts prepared solely for use with such recordings.
  Video recordings and player piano rolls are classified as sound
  recordings."

Media Mail (formerly known as "Book Rate") is very inexpensive.
It is particularly useful if you have more than a couple of rolls to
send.  Keep in mind, however, this is about the lowest class of mail
and, depending on the time of the year, can take much longer to arrive.
If you have 1 to 5 rolls to send, a good choice is Priority Mail.
The Post Office even supplies free boxes for Priority mail, of which
one size is just perfect for piano rolls and will hold up to five
"standard" size rolls.

I find it interesting to hear QRS was instrumental in having piano
rolls included in this rate as I've never had a QRS order arrive
via USPS, only UPS!

John Miller
Saint Paul, Minnesota, USA
http://www.PianoRollStuff.com/