Add line item included_tax_amount method to multiply by quantity

app/mailers/producer_mailer.rb

@@ -56,6 +56,6 @@ class ProducerMailer < Spree::BaseMailer
   end
 
   def tax_total_from_line_items(aggregated_line_items)
-    Spree::Money.new aggregated_line_items.values.map(&:included_tax).sum
+    Spree::Money.new aggregated_line_items.values.map(&:included_tax_amount).sum
   end
 end

app/models/spree/line_item_decorator.rb

@@ -52,10 +52,15 @@ Spree::LineItem.class_eval do
     adjustments.included_tax.any?
   end
 
+  # Single
   def included_tax
     adjustments.included_tax.sum(&:included_tax)
   end
 
+  def included_tax_amount
+    included_tax * quantity
+  end
+
   def price_with_adjustments
     # EnterpriseFee#create_locked_adjustment applies adjustments on line items to their parent order,
     # so line_item.adjustments returns an empty array
@@ -77,8 +82,12 @@ Spree::LineItem.class_eval do
     Spree::Money.new(amount_with_adjustments, { :currency => currency })
   end
 
-  def display_included_tax
-    Spree::Money.new(included_tax, { :currency => currency })
+  def display_included_tax_amount
+    Spree::Money.new(included_tax_amount, { :currency => currency })
+  end
+
+  def display_amount_without_tax
+    Spree::Money.new(amount_with_adjustments - included_tax_amount, { currency: currency })
   end
 
   def display_name

spec/models/spree/line_item_spec.rb

@@ -124,6 +124,15 @@ module Spree
           expect(li_no_tax.included_tax).to eq 0.00
         end
       end
+
+      context "scaling included tax by quantity" do
+        it "multiplies included_tax" do
+          li_tax.quantity = 3
+          li_tax.save
+          expect(li_tax.included_tax).to eq 10.00
+          expect(li_tax.included_tax_amount).to eq 30.00
+        end
+      end
     end
 
     describe "unit value/description" do