The items are stored in the same order the items are stored in the
object that L</calculate_taxes_and_prices> has been called on.
+For example:
+
+ my $invoice = SL::DB::Invoice->new(id => 12345)->load;
+ my %data = $invoice->calculate_prices_and_taxes;
+ my $second_item = $invoice->items->[1];
+
+ print "line total of second item: " . $data{items}->[ $second_item->id ]->{linetotal};
+
=back
=back