Thanks Mike,
So i need to use woocommerce_cart_calculate_fees instead of woocommerce_before_calculate_totals.
function calculate_gift_wrap_fee( $cart_object ) {
/* Gift wrap price */
$additionalPrice = 100;
foreach ( $cart_object->cart_contents as $key => $value ) {
if( isset( $value[“gift_wrap_fee”] ) ) {
$orgPrice = floatval( $value[‘data’]->price );
$value[‘data’]->price = ( $orgPrice + $additionalPrice );
}
}
}
add_action( ‘woocommerce_cart_calculate_fees’, ‘calculate_gift_wrap_fee’, 99 );