You can use

$o=sprintf "%10.4e",$o;
print "$o\n";
[download]

to round up the value of $o at 5 significant digits. The result is:

1.4100e-03
1.9881e-06
2.8032e-09
3.9525e-12
5.5730e-15
7.8579e-18
1.1080e-20
1.5623e-23
2.2028e-26
3.1059e-29
4.3793e-32
[download]

If you don't like it to be in scientific notation you can add a $o+=0; between the two lines to force the value back to numeric:

0.00141
0.0000019881
0.0000000028032
0.0000000000039525
0.000000000000005573
0.0000000000000000078579
0.00000000000000000001108
0.000000000000000000000015623
0.000000000000000000000000022028
0.000000000000000000000000000031059
0.000000000000000000000000000000043793
[download]