So Data::Dumper is throwing me off and Tie::IxHash just might be keeping them in order as advertised.

It's unlikely that Data::Dumper has anything to do with it. As others have written, my guess would be that selectall_arrayref() is returning a reference to an entirely separate hash it generates and populates internally. After all, how would this function "know" that you want it to use the hash referred to by $data to populate with the data it is to return? I can't use Tie::IxHash to produce an example ATM, but consider:

c:\@Work\Perl\monks>perl -wMstrict -le
"package Foo::Bar { sub TIEHASH {} }
 ;;
 my $data = {};
 tie %$data, 'Foo::Bar';
 print $data;
 ;;
 $data = return_anon_hash_ref();
 print $data;
 ;;
 use Data::Dumper;
 print Dumper $data;
 ;;
 sub return_anon_hash_ref { return { 'sorry' => 'charley' }; }
"
HASH(0x3bd06c)
HASH(0x3bd15c)
$VAR1 = {
          'sorry' => 'charley'
        };
[download]

Bottom line: Write your own data display loop or routine and use whatever explicit key order you want.