I took some of your code, some of my own and added in jeffa's summation snippet for good measure.

#! /usr/local/bin/perl
use diagnostics;
use warnings;
use strict;
use Games::Dice 'roll_array';   # this module rocks (well rolls anyway
+ ;-)
use List::Util qw(sum);

my $rolls = 6;

for my $roll (1 .. $rolls) {    # how many sets of dice rolls determin
+ed by the value of $rolls
  my @rolls = roll_array '4d6'; # magic ;-)
  print "raw rolls: @rolls\n";
  @rolls = sort @rolls;         # sorted lowest to highest
  shift @rolls;                 # remove the lowest value by shifting 
+it off
  print "top three rolls: @rolls\n";
  my $sum = sum(@rolls);        # List::Util's sum
  print "total: $sum\n";
}
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