Add variable fee AND fixed fee

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// Calculate service fees

add_action( ‘woocommerce_cart_calculate_fees’,’woocommerce_custom_surcharge’ );

function woocommerce_custom_surcharge() {
global $woocommerce;

if ( is_admin() && ! defined( ‘DOING_AJAX’ ) )
return;

$minimumorder = 20;
if ($woocommerce->cart->cart_contents_count < $minimumorder){
$servicefee = 18.00;
} else {
$plainfee = .90;
$servicefee = 0.00;
// loop through the cart
foreach ( $woocommerce->cart->get_cart() as $cart_item_key => $values ) {
$servicefee += $values[‘quantity’] * $plainfee ;
}
}
}
$woocommerce->cart->add_fee( ‘Service Fee’, $servicefee, true, ‘standard’ );
}