Inclusive tax for deduction and manipulation of tax amount to fix rounding issue

erpnext/buying/doctype/purchase_common/purchase_common.js

@@ -159,6 +159,9 @@ erpnext.buying.BuyingController = erpnext.TransactionController.extend({
 			this.calculate_taxes_and_totals();
 		}
 	},
+	add_deduct_tax: function(doc, cdt, cdn) {
+		this.calculate_taxes_and_totals();
+	},
 
 	calculate_outstanding_amount: function() {
 		if(this.frm.doc.doctype == "Purchase Invoice" && this.frm.doc.docstatus < 2) {

erpnext/controllers/taxes_and_totals.py

@@ -116,21 +116,8 @@ class calculate_taxes_and_totals(object):
 				item.net_rate = flt(item.net_amount / item.qty, item.precision("net_rate"))
 				item.discount_percentage = flt(item.discount_percentage, item.precision("discount_percentage"))
 
-
 				self._set_in_company_currency(item, ["net_rate", "net_amount"])
 
-				# below part need to be fixed???
-
-				# if item.discount_percentage == 100:
-				# 	item.price_list_rate = item.net_rate
-				# 	item.base_price_list_rate = flt(item.price_list_rate*self.doc.conversion_rate,
-				# 		self.doc.precision("base_price_list_rate", item))
-				# 	item.rate = item.base_rate = item.net_rate = item.base_net_rate = 0.0
-				# else:
-				# 	item.base_price_list_rate = flt(item.net_rate / (1 - (item.discount_percentage / 100.0)),
-				# 		self.doc.precision("price_list_rate", item))
-
-
 	def _load_item_tax_rate(self, item_tax_rate):
 		return json.loads(item_tax_rate) if item_tax_rate else {}
 
@@ -155,6 +142,8 @@ class calculate_taxes_and_totals(object):
 				current_tax_fraction = (tax_rate / 100.0) * \
 					self.doc.get("taxes")[cint(tax.row_id) - 1].grand_total_fraction_for_current_item
 
+		if getattr(tax, "add_deduct_tax", None):
+			current_tax_fraction *= -1.0 if (tax.add_deduct_tax == "Deduct") else 1.0
 		return current_tax_fraction
 
 	def _get_tax_rate(self, tax, item_tax_map):
@@ -286,17 +275,13 @@ class calculate_taxes_and_totals(object):
 	def manipulate_grand_total_for_inclusive_tax(self):
 		# if fully inclusive taxes and diff
 		if self.doc.get("taxes") and all(cint(t.included_in_print_rate) for t in self.doc.get("taxes")):
-
 			last_tax = self.doc.get("taxes")[-1]
-
-			diff = self.doc.net_total - flt(last_tax.total / self.doc.conversion_rate,
-				self.doc.precision("grand_total"))
+			diff = self.doc.total - flt(last_tax.total, self.doc.precision("grand_total"))
 
 			if diff and abs(diff) <= (2.0 / 10**last_tax.precision("tax_amount")):
-				adjustment_amount = flt(diff * self.doc.conversion_rate, last_tax.precision("tax_amount"))
-				last_tax.tax_amount += adjustment_amount
-				last_tax.tax_amount_after_discount_amount += adjustment_amount
-				last_tax.total += adjustment_amount
+				last_tax.tax_amount += diff
+				last_tax.tax_amount_after_discount_amount += diff
+				last_tax.total += diff
 
 	def calculate_totals(self):
 		self.doc.grand_total = flt(self.doc.get("taxes")[-1].total

erpnext/public/js/controllers/taxes_and_totals.js

@@ -135,14 +135,6 @@ erpnext.taxes_and_totals = erpnext.stock.StockController.extend({
 				item.net_rate = flt(item.net_amount / item.qty, precision("net_rate", item));
 
 				me.set_in_company_currency(item, ["net_rate", "net_amount"]);
-
-				// if(item.discount_percentage == 100) {
-				// 	item.base_price_list_rate = item.base_rate;
-				// 	item.base_rate = 0.0;
-				// } else {
-				// 	item.base_price_list_rate = flt(item.base_rate / (1 - item.discount_percentage / 100.0),
-				// 		precision("base_price_list_rate", item));
-				// }
 			}
 		});
 	},
@@ -168,6 +160,9 @@ erpnext.taxes_and_totals = erpnext.stock.StockController.extend({
 			}
 		}
 
+		if(tax.add_deduct_tax) {
+			current_tax_fraction *= (tax.add_deduct_tax == "Deduct") ? -1.0 : 1.0;
+		}
 		return current_tax_fraction;
 	},
 
@@ -332,15 +327,12 @@ erpnext.taxes_and_totals = erpnext.stock.StockController.extend({
 			if (all_inclusive) {
 				var last_tax = me.frm.doc["taxes"].slice(-1)[0];
 
-				var diff = me.frm.doc.net_total
-					- flt(last_tax.total / me.frm.doc.conversion_rate, precision("grand_total"));
+				var diff = me.frm.doc.total - flt(last_tax.total, precision("grand_total"));
 
 				if ( diff && Math.abs(diff) <= (2.0 / Math.pow(10, precision("tax_amount", last_tax))) ) {
-					var adjustment_amount = flt(diff * me.frm.doc.conversion_rate, 
-							precision("tax_amount", last_tax));
-					last_tax.tax_amount += adjustment_amount;
-					last_tax.tax_amount_after_discount += adjustment_amount;
-					last_tax.total += adjustment_amount;
+					last_tax.tax_amount += diff;
+					last_tax.tax_amount_after_discount += diff;
+					last_tax.total += diff;
 				}
 			}
 		}