Kmart, since when does "FREE" mean $25?

Now, in general, $10 off $25 is actually a pretty good deal, being approximately 40% off (I'm assuming you'll incur some mailing & time costs, and spending exactly $25 is hard, so it's not quite 40%). You might have had some pretty happy customers if you advertised $10 cash back on $25 purchase.

Instead, I imagine, you've got upset customers now. Congratulations.