Скидка

add_action( 'woocommerce_cart_calculate_fees', 'custom_discount_for_pickup_shipping_method', 10, 1 );
function custom_discount_for_pickup_shipping_method( $cart) {
$percentage = 10;
$categories = array('pizza');
foreach($cart->get_cart() as $cart_item) {

if (has_term( $categories , 'product_cat' , $cart_item['product_id'])) {

$discount = ($cart_item['data']->get_price('edit') * $cart_item['quantity'] * $percentage)/100;

if($discount > 0){
$cart->add_fee( __('Cкидка') . ' (' . $percentage . '%)', -$discount = round( $discount, 1 , PHP_ROUND_HALF_DOWN) );
}
}
}
}