#!perl
use strict;
use warnings;
use XML::Twig;
use Data::Dump 'pp';

my %hash=();
my $twig = new XML::Twig( 
  twig_handlers =>{ 'SellerInformation' => \&info } );
$twig->parsefile('test.xml');

pp \%hash;

sub info {
  my ($t,$e) = @_;
  my $id  = $e->first_child("Seller")->att('sellerIdFromProvider');
  my $col = $e->first_child("TaxableLocationsCollection");
  for my $loc ($col->descendants("TaxableLocation")){
    push @{$hash{$id}}, $loc->att('locationValue');
  }
}