Here's some quick test code I wrote up:

%songs = (
      'Insomina' =>
      {
          'sales' => '9999',
          'votes' => '1'
          },
      'Enter Sandman' =>
      {
          'sales' => '9998',
          'votes' => '10'
          },
      'Bad Moon Rising' =>
      {
          'sales' => '9997',
          'votes' => '9'
          }
      );

sub bysales { $songs{$b}{sales} <=> $songs{$a}{sales}; }
sub byvotes { $songs{$b}{votes} <=> $songs{$a}{votes}; }

# Print the best songs by sales
foreach $ditty ( sort bysales keys songs ) { print "$ditty\n"; }
# Print the best songs by votes
foreach $ditty ( sort byvotes keys songs ) { print "$ditty\n";
[download]

Of course, TMTOWTDI, as usual.
HTH!