คำนวณราคารวมสินค้าทั้งหมด รบกวนช่วยแนะให้หน่อย ตอนนี้ได้เพียงแค่ คำนวณราคาสินค้าต่อชิ้น

<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<form name="form1" method="post" action="order_save.php">
  <table width="100%" border="0" cellpadding="0" cellspacing="0">
    <tr>
      <td><table width="100%" border="1" cellpadding="0" cellspacing="0">
        <?
    	include('conn.php');
		
		$sql = "select * from product ";
		$query = mysql_db_query($dbname,$sql)or die(mysql_error());
		if(mysql_num_rows($query)>0)
			{ 
    ?>
        <tr>
          <td width="5%"><div align="center"><font color="#FF0000">ลำดับ</font></div></td>
          <td width="29%"><div align="center"><font color="#FF0000">ชื่อสินค้า</font></div></td>
          <td width="16%"><div align="center"><font color="#FF0000">ราคา</font></div></td>
          <td width="17%"><div align="center"><font color="#FF0000">จำนวนที่ต้องการซื้อ</font></div></td>
          <td width="15%"><div align="center"><font color="#FF0000">รวมเงิน</font></div></td>
        </tr>
        <?
		while($rsst=mysql_fetch_object($query))
		{
			$proid = $rsst-> pro_id;
			$proname = $rsst-> pro_name;
			$proprice = $rsst->pro_price;
			$x++;
    ?>
        <tr>
          <td><div align="center">
              <?=$x?>
              <input type="hidden" name="proid[<?=$x-1;?>]" id="proid[<?=$x-1;?>]" value="<?=$proid?>">
          </div></td>
          <td><div align="center">
              <?=$proname?>
          </div></td>
          <td><div align="center">
              <?=$proprice?>
          </div></td>
          <td><div align="center">
                <input type="text" name="num<?=$proid?>" id="num<?=$proid?>" autocomplete="off" onKeyDown=" if(this.value==0) this.value = '';"  onKeyUp="if(this.value==0) this.value=0;document.all.total<?=$proid?>.value= parseFloat(document.all.num<?=$proid?>.value)*<?=$proprice?>;" value="0">
              </div></td>
          <td><div align="center">
                <input type="text" name="total<?=$proid?>" id="total<?=$proid?>" value="0">
              </div></td>
        </tr>
        <?
		}
		}
			else
		{
			echo "<div align=\"center\"><font color=\"#FF0000\" size=\"2\">ไม่มีข้อมูล</font></div>";
		}
    ?>
      </table></td>
    </tr>
    <tr>
      <td>&nbsp;</td>
    </tr>
    <tr>
      <td><input type="submit" name="button" id="button" value="บันทึก"></td>
    </tr>
  </table>
</form>