MrShorty wrote...
....
If not, then the easiest way I know of to get three sig figs is to use
a scientific number format (0.00E+0), but a lot of people are either
uncomfortable with exponential notation or for some other reason it
isn't desirable.

A function like ROUND(A1,INT(LOG(A1)-2) will return a number to three
....

Arguably simpler to use scientific notation as an intermediate step.

=--TEXT(A1,"0."&REPT("0",SigDig-1)&"E-0")

or hardcoded for 3 significant digits

=--TEXT(A1,"0.00E-0")

This approach also handles nonpositive numbers.