diff --git a/erpnext/controllers/taxes_and_totals.py b/erpnext/controllers/taxes_and_totals.py
index d2a913c..dc58e11 100644
--- a/erpnext/controllers/taxes_and_totals.py
+++ b/erpnext/controllers/taxes_and_totals.py
@@ -113,17 +113,24 @@
 			for item in self.doc.get("items"):
 				self.doc.round_floats_in(item)
 
+				if not item.rate:
+					item.rate = item.price_list_rate
+
 				if item.discount_percentage == 100:
 					item.rate = 0.0
 				elif item.price_list_rate:
 					if item.pricing_rules or abs(item.discount_percentage) > 0:
 						item.rate = flt(item.price_list_rate *
 							(1.0 - (item.discount_percentage / 100.0)), item.precision("rate"))
-						item.discount_amount = item.price_list_rate * (item.discount_percentage / 100.0)
+
+						if abs(item.discount_percentage) > 0:
+							item.discount_amount = item.price_list_rate * (item.discount_percentage / 100.0)
+
 					elif item.discount_amount or item.pricing_rules:
 						item.rate =  item.price_list_rate - item.discount_amount
 
-				if item.doctype in ['Quotation Item', 'Sales Order Item', 'Delivery Note Item', 'Sales Invoice Item', 'POS Invoice Item', 'Purchase Invoice Item', 'Purchase Order Item', 'Purchase Receipt Item']:
+				if item.doctype in ['Quotation Item', 'Sales Order Item', 'Delivery Note Item', 'Sales Invoice Item',
+					'POS Invoice Item', 'Purchase Invoice Item', 'Purchase Order Item', 'Purchase Receipt Item']:
 					item.rate_with_margin, item.base_rate_with_margin = self.calculate_margin(item)
 					if flt(item.rate_with_margin) > 0:
 						item.rate = flt(item.rate_with_margin * (1.0 - (item.discount_percentage / 100.0)), item.precision("rate"))