How can you round any number (not just integers > 0) to N significant digits?
For example, if I want to round to three significant digits, I'm looking for a formula that could take:
1,239,451 and return 1,240,000
12.1257 and return 12.1
.0681 and return .0681
5 and return 5
Naturally the algorithm should not be hard-coded to only handle N of 3, although that would be a start.