Keeping some max number of sigfigs would be useful to keep columns a consistent comptime-known width. This would make it easier to align columns centrally while maintaining their alignment across benchmarks.
Maybe this requires something like scientific notation. Relevant for #24.

The other reason it'd be useful is in some cases I get max RSS = "2M" for two different cases, but one is reported to be like 10% lower. The rounding is hiding important info. It'd be nice to see "2.14M" instead.

I'm not sure exactly how many sigfigs would be best and they might differ for each measurement, but I think 3 or 4 might be a good start.