It's called "Bookscan." It's the dirty little secret of publishers. Bookscan reports all sales from major houses that use scanners (obviously, it won't report book sales from local bookstores that still give a paper receipt; it won't capture "bulk" sales to the Ohio GOP convention). But it does get a remarkable amount of the sales down in incontrovertible facts that publishers can't ignore.
We are doing VERY well. We are in the 5th printing---about 53,000 in print, and selling (still) VERY strong. Last week, for ex., we sold about 1000.
Bookscan has really hurt agents who BS, because all the major pub houses pay a fee to belong to Bookscan, and if someone says, "so-and-So's last book sold nearly 75,000 copies" and the publisher pulls it up on Bookscan and it's at 20,000, well . . . .
Oh, I am sorry I thought you were a first time unpublished as of yet author. So you already sold that amount and have a track record - that makes sense now - thanks and best of luck. You should put a link on here for your work.
LS, you magnificent bastard! I read your books! Posted their reviews on here as a recommendation without even knowing you were a member!