var count;

if ($( ".next_bestsellers a" ).length > 0) {

    $( "div.bestsellers div.best_item:nth-child(5)" ).hide();
    $( "div.bestsellers div.best_item:nth-child(6)" ).hide();

    $( ".next_bestsellers a" ).click(function() {
        if(count % 2 == 0) {
            $( "div.bestsellers div.best_item:nth-child(5)" ).hide();
            $( "div.bestsellers div.best_item:nth-child(6)" ).hide();
        } else {
            $( "div.bestsellers div.best_item:nth-child(2)" ).show();
            $( "div.bestsellers div.best_item:nth-child(3)" ).show();
        }
        count++;
    });
}