fix: calculation of gross profit percentage in Gross Profit Report (#27045)

diff --git a/erpnext/accounts/report/gross_profit/gross_profit.json b/erpnext/accounts/report/gross_profit/gross_profit.json
index cd6bac2..5fff3fd 100644
--- a/erpnext/accounts/report/gross_profit/gross_profit.json
+++ b/erpnext/accounts/report/gross_profit/gross_profit.json
@@ -1,16 +1,20 @@
 {
- "add_total_row": 1,
+ "add_total_row": 0,
+ "columns": [],
  "creation": "2013-02-25 17:03:34",
+ "disable_prepared_report": 0,
  "disabled": 0,
  "docstatus": 0,
  "doctype": "Report",
+ "filters": [],
  "idx": 3,
  "is_standard": "Yes",
- "modified": "2020-08-13 11:26:39.112352",
+ "modified": "2021-08-19 18:57:07.468202",
  "modified_by": "Administrator",
  "module": "Accounts",
  "name": "Gross Profit",
  "owner": "Administrator",
+ "prepared_report": 0,
  "ref_doctype": "Sales Invoice",
  "report_name": "Gross Profit",
  "report_type": "Script Report",
diff --git a/erpnext/accounts/report/gross_profit/gross_profit.py b/erpnext/accounts/report/gross_profit/gross_profit.py
index 6d8623c..c949d9b 100644
--- a/erpnext/accounts/report/gross_profit/gross_profit.py
+++ b/erpnext/accounts/report/gross_profit/gross_profit.py
@@ -41,12 +41,14 @@
 
 	columns = get_columns(group_wise_columns, filters)
 
-	for src in gross_profit_data.grouped_data:
+	for idx, src in enumerate(gross_profit_data.grouped_data):
 		row = []
 		for col in group_wise_columns.get(scrub(filters.group_by)):
 			row.append(src.get(col))
 
 		row.append(filters.currency)
+		if idx == len(gross_profit_data.grouped_data)-1:
+			row[0] = frappe.bold("Total")
 		data.append(row)
 
 	return columns, data
@@ -154,6 +156,15 @@
 
 	def get_average_rate_based_on_group_by(self):
 		# sum buying / selling totals for group
+		self.totals = frappe._dict(
+			qty=0,
+			base_amount=0,
+			buying_amount=0,
+			gross_profit=0,
+			gross_profit_percent=0,
+			base_rate=0,
+			buying_rate=0
+		)
 		for key in list(self.grouped):
 			if self.filters.get("group_by") != "Invoice":
 				for i, row in enumerate(self.grouped[key]):
@@ -165,6 +176,7 @@
 						new_row.base_amount += flt(row.base_amount, self.currency_precision)
 				new_row = self.set_average_rate(new_row)
 				self.grouped_data.append(new_row)
+				self.add_to_totals(new_row)
 			else:
 				for i, row in enumerate(self.grouped[key]):
 					if row.parent in self.returned_invoices \
@@ -177,15 +189,25 @@
 					if row.qty or row.base_amount:
 						row = self.set_average_rate(row)
 						self.grouped_data.append(row)
+					self.add_to_totals(row)
+		self.set_average_gross_profit(self.totals)
+		self.grouped_data.append(self.totals)
 
 	def set_average_rate(self, new_row):
+		self.set_average_gross_profit(new_row)
+		new_row.buying_rate = flt(new_row.buying_amount / new_row.qty, self.float_precision) if new_row.qty else 0
+		new_row.base_rate = flt(new_row.base_amount / new_row.qty, self.float_precision) if new_row.qty else 0
+		return new_row
+
+	def set_average_gross_profit(self, new_row):
 		new_row.gross_profit = flt(new_row.base_amount - new_row.buying_amount, self.currency_precision)
 		new_row.gross_profit_percent = flt(((new_row.gross_profit / new_row.base_amount) * 100.0), self.currency_precision) \
 			if new_row.base_amount else 0
-		new_row.buying_rate = flt(new_row.buying_amount / new_row.qty, self.float_precision) if new_row.qty else 0
-		new_row.base_rate = flt(new_row.base_amount / new_row.qty, self.float_precision) if new_row.qty else 0
 
-		return new_row
+	def add_to_totals(self, new_row):
+		for key in self.totals:
+			if new_row.get(key):
+				self.totals[key] += new_row[key]
 
 	def get_returned_invoice_items(self):
 		returned_invoices = frappe.db.sql("""