[interchange] Allow to override item tax calculation with tax value in $Items as tax rates may vary between items.

[Stefan Hornburg]

commit 4acb1f0b7e2474cb32f2935006e91bcef295bd40
Author: Stefan Hornburg (Racke) <racke at linuxia.de>
Date:   Tue Oct 30 12:57:00 2012 +0100

    Allow to override item tax calculation with tax value in $Items as tax rates may vary between items.

 lib/Vend/Payment/PaypalExpress.pm |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/lib/Vend/Payment/PaypalExpress.pm b/lib/Vend/Payment/PaypalExpress.pm
index d5d632d..364efa2 100644
--- a/lib/Vend/Payment/PaypalExpress.pm
+++ b/lib/Vend/Payment/PaypalExpress.pm
@@ -1088,7 +1088,7 @@ return $Tag->deliver({ location => $redirecturl });
 					  description => Vend::Data::item_description($item),
 					  amount => Vend::Data::item_price($item),
 					  comment => Vend::Data::item_field($item, 'comment'),
-					  tax => (Vend::Data::item_price($item)/$itemTotal * $taxTotal),
+					  tax => exists $item->{'tax'} ? $item->{'tax'} : (Vend::Data::item_price($item)/$itemTotal * $taxTotal),
 					  rpAmount => Vend::Data::item_field($item, 'rpamount'),
 					  };