It absolutely could be all of the above! But see I write questions like this fairly frequently: I notice something surprising and don't have a good explanation for it. I then write down the question and pose a couple possible explanations which makes me think of more possible explanations. Frequently I realized that taken together the possibilities I thought of are enough to explain what I was surprised at and I don't even ask the question. Other times, like this one, I still feel like I'm missing something. So I ask the question.

In this case it looks like the biggest thing I missed was how much these sales' values depend upon the moment-to-moment stock prices of the parties involved and so that not rounding them hardly even makes sense, as you and bramflakes point out. Thanks!