Note that there is also a -h option for sort on some systems. For those that lack it I have been using this code, piping the du -h output to it. The %so look-up hash gives to sort order for the scale suffix and allows for systems that use no suffix for bytes as well as those that use "B" instead.

use strict;
use warnings;

use Getopt::Std;
my %opts = ( a => 0 );
getopts( q{a}, \ %opts ) or die qq{\n};

my %so = (
   q{} => 0,
   B   => 0,
   K   => 1,
   M   => 2,
   G   => 3,
   T   => 4,
   E   => 5,
   P   => 6,
   Z   => 7,
   Y   => 8,
   );

my $rcSortAscending  = sub
   {
       my( $raA, $raB ) = @_;

       return
          $so{ $raA->[ 2 ] } <=> $so{ $raB->[ 2 ] }
          ||
          $raA->[ 1 ] <=> $raB->[ 1 ]
   };

print
   map  {
            my( $line, $path ) = @$_[ 0, 3 ];
            if ( $path !~ m{/$} and -d $path and not -l $path )
            {
                $line =~ s{\n}{/\n};
            }
            $line;
        }
   sort {
            $opts{ a }
            ? $rcSortAscending->( $a, $b )
            : $rcSortAscending->( $b, $a )
        }
   map  { [ $_, m{^\s*([\d.]+)([BKMGTEPZY]?)\s+(.*)} ] }
   <>;
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I hope this is helpful.