Has been working ok for hundreds of millions, so there's that.
Almost all drugs are sold in "nice round numbers" anyway.
Given that you can drop orders of magnitude in scale from grams to milligrams (or whatever) to suite the dosage calculation, nobody is going to notice the difference between X with decimal points and Y which is X rounded, as if 247.3mg was going to be optimal and 250 will be bad.
The variability of what the patient actually needs (e.g. an adult male could be 1.55 and 50kg to 2.10 and 150kg but they usually just get the same dosage in the instructions - and for most drugs no doctor would bother to suggest a more fitting value) would be higher than any rounding error anyway, but in practice it hardly matters.
Has been working ok for hundreds of millions, so there's that.
Almost all drugs are sold in "nice round numbers" anyway.
Given that you can drop orders of magnitude in scale from grams to milligrams (or whatever) to suite the dosage calculation, nobody is going to notice the difference between X with decimal points and Y which is X rounded, as if 247.3mg was going to be optimal and 250 will be bad.
The variability of what the patient actually needs (e.g. an adult male could be 1.55 and 50kg to 2.10 and 150kg but they usually just get the same dosage in the instructions - and for most drugs no doctor would bother to suggest a more fitting value) would be higher than any rounding error anyway, but in practice it hardly matters.