Update

app/assets/javascripts/payment.js

@@ -0,0 +1,40 @@
+// number key pad
+$(document).on('click', '.cashier_number', function(event){
+        event.stopPropagation();
+        event.preventDefault();
+        if(event.handled !== true) {
+            var original_value;
+            original_value = $('#amount').text();
+
+            var input_value = $(this).attr("data-value");
+
+            var input_type = $(this).attr("data-type");
+            	switch (input_type) {
+              		case 'num':
+		              	if (original_value == "0.0"){
+			                $('#amount').text(input_value);
+			            }else{
+			                $('#amount').append(input_value);
+			            }
+              		break;
+
+              		case 'add':
+	                	var input_value = $(this).attr("data-value");
+	                	amount = parseInt(input_value) + parseInt(original_value);
+	                	$('#amount').html(amount);
+
+             		break;
+             		case 'clr':
+             			$('#amount').html("0.0");
+             		break;
+             		case 'del' :
+			          var cash=$('#amount').text();
+			          $('#amount').text(cash.substr(0,cash.length-1));
+			        break;
+
+          		}
+          	event.handled = true;
+        } else {
+            return false;
+        }
+});