add_action('woocommerce_checkout_update_order_review', function($data) {
global $WOOCS;

if (is_string($data)) {
parse_str($data, $data);
}
$_currency = $WOOCS->get_currency_by_country($data['shipping_country']);

if (!empty($_currency)) {
$WOOCS->set_currency($_currency);
$_GET['currency']=$_currency;
}
}, 9999);