See sprintf  %g format specifier: 
>perl -wMstrict -le
"my @nra = (
 8.8458e-119,
 1.06542e-52,
 2.68e-36,
 2.91405e-35,
 0.0190644,
 0.0205511,
 0.004,
 );
 for my $n (@nra) {
   my $fmt = $n > 0.001 ? '%5.2g' : '%5.3g';
   printf qq{$fmt \n}, $n;
   }
"
8.85e-119
1.07e-052
2.68e-036
2.91e-035
0.019
0.021
0.004

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Update: This loop produces the same output without needing an intermediate variable: 
printf qq{%5.*g \n}, $_ > 0.001 ? 2 : 3, $_ for @nra;

[download]

In reply to Re: Round numbers? by AnomalousMonk
in thread Round numbers? by Anonymous Monk

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