http://www.perlmonks.org?node_id=1000775


in reply to Best way to round a number.

Maybe not the "best" way, but very flexible: adjust the %rule hash to change the way the rounding will work based upon the last digit and the regex will do all the work (assuming you feed it a positive integer):
use Modern::Perl;

my %rule = (
    0 =>  0,
    1 => -1,
    2 => -2,
    3 =>  2,
    4 =>  1,
    5 =>  0,
    6 => -1,
    7 => -2,
    8 =>  2,
    9 =>  1,
);
my @nums = 0..30;
foreach (@nums) {
    print "in=$_";
    s/(\d*(\d))/$1+$rule{$2}/e;
    say "\t rounded=$_";
}

[download]

CountZero

A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James

My blog: Imperial Deltronics

In Section Seekers of Perl Wisdom