Some of my buckets have X.035 amount of fluid in them. Could it be a FP arithmetic bug?

No, the big bucket holds an integer amount of millibuckets. It is only displayed as a decimal amount of buckets.

Well this is probably a moot point, I stopped playing and archived my server.

Close it up if you think it isn't important. It made my life a bit hard because I couldn't get rid of the last 0.035 fraction and my big buckets suddenly became typed based on the fractional liquid inside.