If you want to have more control over the generated data structure, try XML::Rules. In this case something like:

use strict;
use XML::Rules;

my $parser = XML::Rules->new(
  normalisespaces => 1,
  rules => {
    div => sub {
        if (exists $_[1]->{class}) {
            my $class = delete $_[1]->{class};
            return '@'.$class => $_[1];
        } else {
            return $_[0] => $_[1];
        }
    }
  },
);

my $data = $parser->parse(\*DATA);
use Data::Dumper;
print Dumper($data);

__DATA__
<div id="main">
<div class="A">
    ...
</div>
<div class="A">
    ...
</div>
<div class="A">
    ...
</div>
<div class="B">
    ...
</div>
<div class="B">
    ...
</div>
<div class="B">
    ...
</div>
</div>
[download]