use strict;
use warnings;

use Data::Dumper qw( Dumper );
use XML::SAX     qw( );
use XML::Simple  qw( XMLin );

#$XML::Simple::PREFERRED_PARSER = "XML::Parser";
$XML::Simple::PREFERRED_PARSER = "XML::SAX::Expat";

print(Dumper(XMLin(\*DATA, NSExpand => 1)));

__DATA__
<doc xmlns:xyz="http://a" xmlns:ec="http://b">
   <xyz:CostFee>
      <ec:OPA>25.00</ec:OPA>
      <ec:CTID>278421</ec:CTID>
      <xyz:CDEPSID>82</xyz:CDEPSID>
      <ec:IID>8765654</ec:IID>
   </xyz:CostFee>
</doc>

__END__
$VAR1 = {
          '{http://a}CostFee' => {
                                   '{http://a}CDEPSID' => '82',
                                   '{http://b}CTID' => '278421',
                                   '{http://b}IID' => '8765654',
                                   '{http://b}OPA' => '25.00'
                                 },
          '{http://www.w3.org/2000/xmlns/}xyz' => 'http://a',
          '{http://www.w3.org/2000/xmlns/}ec' => 'http://b'
        };