How can I update the price when someone enters postcode or zip code in woocommerce checkout page?

As I was trying to add some additional amount to my charge and I was unable to update the charge amount. The code which I was trying was this using AJAX call:

$woocommerce->cart->set_total($woocommerce->cart->total + $additional_amount);

But the real problem was with my payment method, not the cart price. So, I resolved it using a filter which happens just before charge amount is about to sent to database and payment gateway.
The code which works for me is this:

function additional_amount($order){
    $total_additional_amount = $amount1 + $amount 2;
    $total_additional_amount = round($total_additional_amount, 2);
    $order->set_total( $total_amount);
}
add_filter( 'woocommerce_checkout_create_order', 'additional_amount', 10, 1 );

Using this filter, I was able to update the actual charge amount.
I hope that will help to someone.