Heath,
In this example from another artist, the artwork was uploaded June 2011; notice the same $.21 discrepancy you're experiencing. Random selections from other various artists are not producing errors, but I only checked a few images.
For example, one selection from an artist uploaded 2014 did not show any errors. Artist Mystic Sparrow commented in this thread, that they, too, have noticed the same discrepancy on their work. I pulled one of their images and it seemed to be okay, so I do not know which one they are referring to. But I take them at their word.
I have no experience in coding; however, for inconsistencies to appear on both older and newer uploads from two (& potentially three - or who knows exactly how many) completely random artists, and in some cases artwork uploaded years apart, can only suggest a discrepancy behind the scenes somewhere.
I hope this helps in explaining the anomaly.
Good luck, brother.
Jeff