My brother is left handed and I am averse to unwarranted levels of numerical precision, so perhaps there really is something to this.
NCBI ROFL: Left-handed people avoid using exact numbers. : Discoblog.
The extension of the effect to “the familial sinistral group” with the hypothesis that “their language and number systems tend to be more distributed over both hemispheres of the brain” is interesting.
But I would attribute my own rounding behaviour less to the greater “cognitive effort of using exact numbers” than to understanding the stupidity of wasting any effort beyond what is actually useful.
Indeed the hypothesis of cross hemispheric distribution of the linguistic-computational system may be considered to imply a possibly better integration of the digital and analog systems and so a better overall level of numeracy. Which may explain the ‘left handed nerds’ aspect of this other article (although a simpler explanation may be just that many sports are based on interacting with dexterity and only the particularly talented subset of the non-dextrous are capable of employing that deficit with sufficient success to be dangerously sinister).