Is there any way to show the data in a tabular format without using "\n\t"?.

Yes, you can use printf or format

Is there any perl function that will sum all the values in a hash?

Not that I am aware of, but it's quite trivial to do that by adding an extra line to your loop above, eg:

$total_count += $dir_file_counts{$_};
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Update: And here is an example using printf

#!/usr/bin/perl -w
use strict;

my %dir_file_counts = ( xbags => 416,
                     apr => 28,
                     apam =>  1,
                     asrs =>  431,
                     aast => 181,
                     xpept => 8,
                     xbank => 178,
                     aprot => 28 );

my $total_count = 0;

print "\n Total Number of files \n\n";
foreach(keys %dir_file_counts) {
  $total_count += $dir_file_counts{$_};
    printf "%12s => %5s\n",
        $_,
        $dir_file_counts{$_},
}

printf "%12s => %5s\n", "Grand Total", $total_count;
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Cheers,
Darren :)