diff --git a/erpnext/accounts/doctype/payment_request/payment_request.py b/erpnext/accounts/doctype/payment_request/payment_request.py
index 52eb29b3bb..2f43914c45 100644
--- a/erpnext/accounts/doctype/payment_request/payment_request.py
+++ b/erpnext/accounts/doctype/payment_request/payment_request.py
@@ -495,7 +495,7 @@ def get_amount(ref_doc, payment_account=None):
 	"""get amount based on doctype"""
 	dt = ref_doc.doctype
 	if dt in ["Sales Order", "Purchase Order"]:
-		grand_total = flt(ref_doc.grand_total) - flt(ref_doc.advance_paid)
+		grand_total = flt(ref_doc.rounded_total) - flt(ref_doc.advance_paid)
 
 	elif dt in ["Sales Invoice", "Purchase Invoice"]:
 		if ref_doc.party_account_currency == ref_doc.currency: