fix in tax calc in tax_controller
diff --git a/controllers/tax_controller.py b/controllers/tax_controller.py
index 7aa8e23..d70ba3e 100644
--- a/controllers/tax_controller.py
+++ b/controllers/tax_controller.py
@@ -140,7 +140,7 @@
 		self.doc.net_total = flt(self.doc.net_total, self.precision.main.net_total)
 		self.doc.fields[self.fmap.net_total_print] = \
 			flt(self.doc.fields.get(self.fmap.net_total_print),
-			self.precision.main[self.fmap.net_total_print])
+			self.precision.main.get(self.fmap.net_total_print))
 			
 	def calculate_taxes(self):
 		for item in self.item_doclist: