use List::Util qw/ sum /;

   # calculate total number of seconds
   $seconds = sum map {
         my ($m,$s) = split /:/;
         $m*60 + $s
     }
     qw/ 01:45 60:00 45:25 /;     # or your array with times

   $minutes = int($seconds / 60); # integral number of minutes
   $seconds = $seconds % 60;      # remaining seconds

   $new_time = sprintf "%02d:%02d", $minutes, $seconds;