I don't feel too strongly about this, but I chose floor because it seemed better to me to pick the smaller number always.  The fact of the matter is that 100 and 101 are not very different.  Same with 45 and 46 (you're gonna be treating for either of them) as well as 201 and 202.

I believe this is the same for mmol/L.  2.2 and 2.3 are both going to be "treat now", 4.7 and 4.8 will both be "yay" and 8.0 and 8.1 will both be "hrm, I need some more insulin".  So, it just seemed better to me to err on the side of the smaller number (if there *is* a functional difference between just one unit, then it is better to err on the side of treating a low that might have been fine untreated than to not treat a low that should be treated).