main.py

 from kivy.app import App
 from kivy.modules import inspector # For inspection.
 from kivy.core.window import Window # For inspection.
+from kivy.properties import NumericProperty
 
 __app_package__ = 'edu.unl.cse.soft161.order'
 __app__ = 'Order Meal'
@@ -9,6 +10,51 @@ __flags__ = ['--bootstrap=sdl2', '--requirements=python2,kivy', '--orientation=l
 
 
 class OrderApp(App):
+
+    subtotal = NumericProperty(0.00)
+    tax = NumericProperty(0.00)
+    total = NumericProperty(0.00)
+    def buttonOne(self):
+        self.subtotal += 5.99
+        self.tax += (self.subtotal * .07)
+        self.total = (self.subtotal + self.tax)
+    def buttonTwo(self):
+        self.subtotal += 7.99
+        self.tax += (self.subtotal * .07)
+        self.total = (self.subtotal + self.tax)
+    def buttonThree(self):
+        self.subtotal += 8.99
+        self.tax += (self.subtotal * .07)
+        self.total = (self.subtotal + self.tax)
+    def buttonFour(self):
+        self.subtotal += 6.99
+        self.tax += (self.subtotal * .07)
+        self.total = (self.subtotal + self.tax)
+    def buttonFive(self):
+        self.subtotal += 6.99
+        self.tax += (self.subtotal * .07)
+        self.total = (self.subtotal + self.tax)
+    def buttonSix(self):
+        self.subtotal += 2.99
+        self.tax += (self.subtotal * .07)
+        self.total = (self.subtotal + self.tax)
+    def buttonSeven(self):
+        self.subtotal += 1.99
+        self.tax += (self.subtotal * .07)
+        self.total = (self.subtotal + self.tax)
+    def buttonEight(self):
+        self.subtotal += 2.99
+        self.tax += (self.subtotal * .07)
+        self.total = (self.subtotal + self.tax)
+    def buttonNine(self):
+        self.subtotal += 1.99
+        self.tax += (self.subtotal * .07)
+        self.total = (self.subtotal + self.tax)
+    def buttonTen(self):
+        self.subtotal += 0.99
+        self.tax += (self.subtotal * .07)
+        self.total = (self.subtotal + self.tax)
+
     def build(self):
         inspector.create_inspector(Window, self) # For inspection (press control-e to toggle).
 

order.kv

 BoxLayout:
     orientation: 'vertical'
     Label:
-        text: '[Your meal-ordering GUI here]'
+        text: 'welcome to restaurant'
+        size_hint: 1,0.20
+    BoxLayout:
+        orientation: 'horizontal'
+        BoxLayout:
+            orientation: 'vertical'
+            Label:
+                text: '1'
+            Label:
+                text: 'Order Chicken Tenders '
+            Button:
+                on_press: app.buttonOne()
+        BoxLayout:
+            orientation: 'vertical'
+            Label:
+                text: '2'
+            Label:
+                text: 'Order Hamburger'
+            Button:
+                on_press:app.buttonTwo()
+        BoxLayout:
+            orientation: 'vertical'
+            Label:
+                text: '3'
+            Label:
+                text: 'Order Cheeseburger'
+            Button:
+                on_press:app.buttonThree()
+        BoxLayout:
+            orientation: 'vertical'
+            Label:
+                text: '4'
+            Label:
+                text: 'Order Chicken Sandwich'
+            Button:
+                on_press:app.buttonFour()
+        BoxLayout:
+            orientation: 'vertical'
+            Label:
+                text: '5'
+            Label:
+                text: 'Order Fish Sandwich'
+            Button:
+                on_press:app.buttonFive()
+    BoxLayout:
+        BoxLayout:
+            orientation: 'vertical'
+            Label:
+                text: '6'
+            Label:
+                text: 'Order French Fries'
+            Button:
+                on_press:app.buttonSix()
+        BoxLayout:
+            orientation: 'vertical'
+            Label:
+                text: '7'
+            Label:
+                text: 'Order Small Pop'
+            Button:
+                on_press:app.buttonSeven()
+        BoxLayout:
+            orientation: 'vertical'
+            Label:
+                text: '8'
+            Label:
+                text: 'Order Large Pop'
+            Button:
+                on_press:app.buttonEight()
+        BoxLayout:
+            orientation: 'vertical'
+            Label:
+                text: '9'
+            Label:
+                text: 'Order Ice Cream'
+            Button:
+                on_press:app.buttonNine()
+        BoxLayout:
+            orientation: 'vertical'
+            Label:
+                text: '10'
+            Label:
+                text: 'Order Pie'
+            Button:
+                on_press:app.buttonTen()
+    BoxLayout:
+        size_hint: 1,0.20
+        orientation: 'horizontal'
+        Label:
+            text: 'Subtotal: ' + str(app.subtotal)
+        Label:
+            text: 'Tax: ' + str(app.tax)
+        Label:
+            text: 'Total: ' + str(app.total)