Asymmetry of significant figures

From Why start at x, y, z

The bounds on a value given to a number of significant figures are not symmetric when the value given is a power of 10.

For example, if \( x = 1000 \) to two significant figures, then \( 995 \le x \lt 1050 \). The lower bound is 5 smaller than 1000, while the upper bound is 50 larger.

Tom Bowler led a twitter discussion on a related topic.