Unless you need to store the values for later use, I'd do it this way:

use strict;
use warnings;

while(<DATA>) {
   if(/([\w\s]+:)\s([a-z]+)(\d+)\2/) {
    print "$1 ", sprintf("%5.2f\n",$3*0.4/100); 
  }
}

__DATA__
Today: today408today
Clicks: 34
Yesterday: yesterday555yesterday
Clicks: 61
This Month: this11360this
Clicks: 812
Last Month: last5350last
Clicks: 454
[download]

which gives

Today:  1.63
Yesterday:  2.22
This Month: 45.44
Last Month: 21.40
[download]

Edited: Removed unnecessary extra colon in print (I had captured it already from the input) and inserted actual output generated - duh!