The decimal point can make an uncertain guess look professionally dressed.

Adding decimal places makes a number look measured rather than guessed. A figure like sixty-eight point four carries an air of instrumentation, even when it came from an estimate with a margin wide enough to swallow the decimal entirely. The precision is presentational, not real.

When a number looks unusually exact, ask how it was arrived at. Real measurement can support fine detail, estimates cannot, and honest work says which it is. In your own reporting, round to the precision you actually have, since implied confidence is a quiet form of overclaiming.