I recently mailed a nettles which had 0.91 damage (shown in the damage column of the item itself in yellow).
Before I clicked "Send" in the mail dialog box I noticed that in the text where I enter the cod price, the damage column of this item showed a single 0, with no mention of the damage on the nettles.
It is probably a rounding down or truncating error as the figure hasn't met the integer threshold of 1.
I think if possible there should be the correct figure in yellow text in the damage column to alert the sender that the item is damaged even slightly, when adding cod cost - before sending to a buyer.