Wayne:

It would've been easier had you actually included a bit of XML. I went ahead and installed XML::Mini::Document and ran it, but as you can see, I'm not experiencing the problem:

$ cat pm_1231805_to_hash.pl
#!/usr/bin/perl -w
use strict;
use warnings;
use 5.24.1;
use Data::Dumper qw(Dumper);
use XML::Mini::Document;

$Data::Dumper::Terse=1;

my $xml = <<EOXML;
<shipping_tax>0.00</shipping_tax>
 <fee_lines></fee_lines>
 <billing_address>
  <city>Moncton</city>
  <province_code>NB</province_code>
  <country>Canada</country>
  <address_2></address_2>
  <email>someone\@somewhere.com</email>
  <country_code>CA</country_code>
  <province>New Brunswick</province>
  <phone>5065551212</phone>
  <first_name>Joe</first_name>
  <address_1>123 Somestreet</address_1>
  <postal_code>E4E 4E4</postal_code>
  <company_name></company_name>
  <last_name>Blow</last_name>
 </billing_address>
EOXML

my($hash_ref)=&convert_xml_to_hash($xml);

my $data=eval($hash_ref);

say Dumper($data);

exit;

sub convert_xml_to_hash
{
        my($xml)=(@_);
        my($hash)={};

        if($xml)
        {
                my($xml_object)=XML::Mini::Document->new();
                $xml_object->parse($xml);

                my($output)=$xml_object->toHash();
                $hash=Dumper($output);
        }
        return($hash);
}

Roboticus@Waubli ~
$ perl pm_1231805_to_hash.pl
{
  'shipping_tax' => '0.00',
  'fee_lines' => '',
  'billing_address' => {
                         'province' => 'New Brunswick',
                         'country' => 'Canada',
                         'address_2' => '',
                         'last_name' => 'Blow',
                         'company_name' => '',
                         'province_code' => 'NB',
                         'phone' => '5065551212',
                         'country_code' => 'CA',
                         'email' => 'someone@somewhere.com',
                         'postal_code' => 'E4E 4E4',
                         'city' => 'Moncton',
                         'address_1' => '123 Somestreet',
                         'first_name' => 'Joe'
                       }
}
[download]

Perhaps you have either (a) some wonky data, or (b) a bit of code you've not shown us is frobnicating it somewhere.

Edit: I forgot to mention that I didn't build the input by hand. Since you at least provided some output, I edited the output to make it what you wanted. I then used XML::Mini::Document to rebuild the input (code in the readmore tags below).

#!/usr/bin/perl -w
use warnings;
use strict;
use XML::Mini::Document;
use 5.24.1;

my $xmlDoc = XML::Mini::Document->new();
my $data = {
'billing_address' => {
     'province' => 'New Brunswick',
     'city' => 'Moncton',
     'company_name' => '',                   # Should be company_name
     'phone' => '5065551212',
     'address_2' => '',                      # Should be address_2
     'country_code' => 'CA',
     'first_name' => 'Joe',
     'address_1' => '123 Somestreet',
     'email' => 'someone@somewhere.com',
     'country' => 'Canada',
     'postal_code' => 'E4E 4E4',
     'last_name' => 'Blow',
      'province_code' => 'NB'
     },
     'fee_lines' => '',                      # should be fee_lines
     'shipping_tax' => '0.00',
};
$xmlDoc->fromHash($data);
print $xmlDoc->toString();
[download]