my %final_href;
merge_jsons(".data.json",\@dirs,\%final_href);

sub merge_jsons {
    my ($name,$dirs,$final_href) = @_;
    my %data;
    foreach my $dir (@{$dirs})
    {

        decode($dir."/".$name,%data); # will change name
        my $final_href = 
        (
            data => { ( %{$final_href->{data} },%{ $data{data} } ) },
            total => do
            {
              my %total;
              for my $href ( $final_href->{total}, $data{total} ) {
               $total{$_} += $href->{total}{$_} for keys %{ $href->{to
+tal} };
              }
            \%total;
            }
        );
   }
}
[download]

brilliant! xD