To me, yes... To someone I suppose it matters...
To be Honest, I like that the OP has Considered the Actual Volumes that are in a Given Nicotine Base or e-Liquid. I have spent Countless Hours teaching people to Think in Totality when Evaluating a Math Problem. And that Errors Many Times are Based on a Lack of Understanding EXACTLY what you looking at.
But once a Person can Quantify All the Parameters in a Problem, I also think that For Real World Application, some consideration needs to be made to Relative Errors and Tolerances.
As a Math Problem, the Amounts in a Flavored e-Liquid should be Definable to ANY Level of Accuracy. And if a person wants to take them out to a 1,000 Decimal Places, so be it. They're just Numbers.
But as a Mixing Problem where Taste is Highly subjective, and where levels of Measuring Accuracy are Usually Exceeded after 2 Decimal Places, I sometimes Question how much Accuracy is Needed?