Fixes in purchase register report (#12737)

diff --git a/erpnext/accounts/report/item_wise_sales_register/item_wise_sales_register.py b/erpnext/accounts/report/item_wise_sales_register/item_wise_sales_register.py
index ab5251f..8917c9f 100644
--- a/erpnext/accounts/report/item_wise_sales_register/item_wise_sales_register.py
+++ b/erpnext/accounts/report/item_wise_sales_register/item_wise_sales_register.py
@@ -168,11 +168,11 @@
 
 	for d in item_list:
 		invoice_item_row.setdefault(d.parent, []).append(d)
-		item_row_map.setdefault(d.parent, {}).setdefault(d.item_code, []).append(d)
+		item_row_map.setdefault(d.parent, {}).setdefault(d.item_code or d.item_name, []).append(d)
 
 	conditions = ""
 	if doctype == "Purchase Invoice":
-		conditions = " and category in ('Total', 'Valuation and Total')"
+		conditions = " and category in ('Total', 'Valuation and Total') and base_tax_amount_after_discount_amount != 0"
 
 	tax_details = frappe.db.sql("""
 		select
diff --git a/erpnext/accounts/report/purchase_register/purchase_register.py b/erpnext/accounts/report/purchase_register/purchase_register.py
index 37848d5..610475a 100644
--- a/erpnext/accounts/report/purchase_register/purchase_register.py
+++ b/erpnext/accounts/report/purchase_register/purchase_register.py
@@ -172,6 +172,7 @@
 		else sum(base_tax_amount_after_discount_amount) * -1 end as tax_amount
 		from `tabPurchase Taxes and Charges`
 		where parent in (%s) and category in ('Total', 'Valuation and Total')
+			and base_tax_amount_after_discount_amount != 0
 		group by parent, account_head, add_deduct_tax
 	""" % ', '.join(['%s']*len(invoice_list)), tuple([inv.name for inv in invoice_list]), as_dict=1)