First version.

cashier.php

@@ -0,0 +1,58 @@
+<?php
+/**
+ * Basic cash register system.
+ * @author: Jacob McCloughan
+ * @version: 4/09/2017
+ */
+
+// Variables
+$input = "";
+$subtotal = 0;
+$total = 0;
+define("tax", .06);
+$items = array();
+
+// Loop for driving price entry
+while(true) {
+    $input = readline("Insert a value (type 'stop' to stop): ");
+    if ($input == "stop") {
+        echo "Entry halted.\n";
+        break;
+    }
+    if (!is_numeric($input)) {
+        echo "Invalid value. Try again.\n";
+    }
+    echo "Item added.\n";
+    $input = round((float)$input, 2);
+    array_push($items, $input);
+}
+
+// Calculates and prints receipt
+$subtotal = array_sum($items);
+$total = round(($subtotal + ($subtotal * tax)), 2);
+echo "\nReceipt:\n";
+foreach ($items as $num=>$item) {
+    echo "Item #" . ($num + 1) . " Price: " . $item . "\n";
+}
+echo "\nSubtotal: " . $subtotal . "\n";
+echo "Tax: " . round(($subtotal * tax), 2) . "\n";
+echo "Total: " . $total . "\n\n";
+
+// Loop for driving change entry
+while(true) {
+    if ($total < 0) {
+        echo "\nYour change is " . round((-1 * $total), 2) . ". Have a nice day.\n";
+        break;
+    } else if ($total == 0) {
+        echo "\nHave a nice day.\n";
+    }
+    $input = readline("Insert payment value: ");
+    if (!is_numeric($input)) {
+        echo "Invalid value. Try again.\n";
+    }
+    $total = round($total - (float)$input, 2);
+    if ($total > 0) {
+        echo "Remaining total is: " . $total . "\n";
+    }
+}
+?>