Totaling multiple sums in one array

I have a table with entries for ItemID and Amount ... I am querying this table and displaying the contents from the previous date by itemID and amount. I have the array grouping the items by Item ID what would like to be able to do is to get a total amount of ordered items for each ItemID.

For example what I have now is this:
Item 1 / Amount 12
Item 1 / Amount 50
------------------------------
Item 2 / Amount 5
Item 2 / Amount 7
Item 2 / Amount 3

and so on ... what I woul like to have is:

Item 1 / Total Amount: 62
------------------------------
Item 2 / Total Amount: 15

I have been sucessful in totaling the entire amount column for all items but not in getting the individual item totals.

My current code is as follows:

// Connect to the database 
  $dbc = mysqli_connect(DB_HOST, DB_USER, DB_PASSWORD, DB_NAME);
  $query = 'SELECT o.OrderID, o.OrderDate, od.DetailItemName,od.DetailItemID,od.DetailQuantity, od.OrderID FROM orders AS o INNER JOIN orderdetails AS od USING(OrderID) WHERE TO_DAYS(OrderDate) = TO_DAYS(CURDATE() - INTERVAL 1 DAY) ORDER BY DetailItemID';
  $data = mysqli_query($dbc, $query);
  $Items = array();
  while ($row = mysqli_fetch_array($data)) {
    array_push($Items, $row);
  }
  mysqli_close($dbc);
  // Generate the  form by looping through the items array
  echo '<p>Total Order Amounts By Item For ' .date("Y/m/d", time()-86400) . ' </p>';
  $ItemID = $Items[0]['DetailItemID'];
  echo '<fieldset><legend>' . $Items[0]['DetailItemName'] . '</legend>';
  foreach ($Items as $Item) {
    // Only start a new fieldset if the ItemID has changed
    if ($ItemID != $Item['DetailItemID']) {
      $ItemID = $Item['DetailItemID'];
      echo '</fieldset><fieldset><legend>' . $Item['DetailItemName'] . '</legend>';
    }
	    // Display the Item and Total number of items form field
    echo 'Item Name ' . $Item['DetailItemName'] . '  / Amount ' . $Item['DetailQuantity'] . ' ';
  }
  echo '</fieldset>'

Thanks for looking,
Eric