And promptly rounded down 5 months, 20 days to only 5 months. Chortle!
“For instance, rounding down is acceptable when doing income taxes, rounding down to the nearest whole dollar”
We are talking about months here, not taxes. Your analogy is not applicable. So sorry.
It is certainly applicable. One can round down to the next whole number, as well as up. It is accepted practice. When someone asks your age, and you are 13 years and 8 months old, you don't say you are 14; you say you are 13. (I think you are probably younger than that, but I digress. I was a paid math tutor at a local college, they found my knowledge quite valuable. Perhaps you should stop being so stubborn and learn a few things.
It is certainly applicable. One can round down to the next whole number, as well as up. It is accepted practice. When someone asks your age, and you are 13 years and 8 months old, you don't say you are 14; you say you are 13. (I think you are probably younger than that, but I digress. I was a paid math tutor at a local college, they found my knowledge quite valuable. Perhaps you should stop being so stubborn and learn a few things.