คำนวณค่า commission จะแสดงผลรวมค่าออกมาต้องใส่ยังไงเหรอคะ

$sql = "SELECT cart.*,bill.* FROM cart,bill WHERE cart.order_id = bill.order_id AND  cart.member_id='$_SESSION[member_id]' ORDER BY cart.eventdate ASC";
$recordSet=$conn->Execute($sql);
$software_id = $recordSet->fields[software_id];

$sql_software = "SELECT * FROM software ";
$sql_software .= " WHERE software_id='$software_id' and statusR ='Y'";

$recordSoftware = $conn->Execute[$sql_software];
$license_type = $recordSoftware->fields[$software_license_type];

function commission($price){
	if($price<=500){
		$result=$price*0.3;	
	}
	else if($price>500 and $price<=1000){
		$result=$price*0.25;
	}
	else if($price>1000 and $price<=5000){
		$result=$price*0.2;
	}
	else if($price>5000 and $price<=10000){
		$result=$price*0.15;
	}
	else{
		$result=$price*0.1;
	}
	return $result;
}
function chk_commission($price){
	if($price<=500){
		$result=30;	
	}
	else if($price>500 and $price<=1000){
		$result=25;
	}
	else if($price>1000 and $price<=5000){
		$result=20;
	}
	else if($price>5000 and $price<=10000){
		$result=15;
	}
	else{
		$result=10;
	}
	return $result;
}

	<table width="100%" border="1">
	  <tr>
		<td>Date</td>
		<td>ID</td>
		<td>Detail</td>
		<td>Credit Out(Baht)</td>
		<td>Credit In(Baht)</td>
		<td>Balance(Baht)</td>
	  </tr>
<? 
while (!$recordSet->EOF)
{
?>
	  <tr>
		<td><?=$recordSet->fields[eventdate]?></td>
		<td><?=$recordSet->fields[cart_id]?></td>
		<td><?=$recordSoftware->fields[software_name]." (Order ID : ".$recordSet->fields[order_id].")" ?></td>
		<td>&nbsp;</td>
		<td><?=$recordSet->fields[price]?></td>
		<td>// ใส่ balance ยังไง</td>
	  </tr>
      <? $commission=$recordSet->fields[price]; ?>
	  <tr>
		<td><?=$recordSet->fields[eventdate]?></td>
		<td><?=$recordSet->fields[cart_id]?></td>
		<td><?="Commission Free - ".chk_commission($commission)."% (Order ID : ".$recordSet->fields[order_id].")"?></td>
		<td>
		<? 
		echo commission($commission);
		?>
        </td>
		<td>&nbsp;</td>
		<td>// ใส่ balance ยังไง</td>
	  </tr>
<?
	$recordSet->MoveNext();
}
?>
	</table>