Woocommerce Taxes问题

Question

I have a big issue with taxes in woocommerce.
I have a product at 2,99 inc. VAT (VAT 7%). But I want to show price with no VAT for some customers.
So price will be 2.79 ex. VAT.
In my setting I have "Yes, I will enter prices inclusive of tax"

With no taxes I have product at 2.79 as I want, but if I order 10 products I see 27.94 !
I know woocommerce round vat with a lot of decimal but I don't want that ! I want to show 27.90 for 10 products !

I tried this :

add_filter( 'woocommerce_get_price_including_tax', 'custom_edit_price_function',99,3);
function custom_edit_price_function($price, $qty, $product) {
    //calculate price how you like it here.
    $tax_rates = reset(WC_Tax::get_rates( $product->get_tax_class()))['rate'];
    $return_price = $product->get_price();
    $price_with_vat = $return_price * ( 1 + ( $tax_rates / 100 ) );
    $price_round = round($price_with_vat, 2);
    $price = $price_round * $qty;
    return $price;
}

And I have 27.90 for item total but i still have 27.94 in cart total !

Does someone have an idea ? This drives me crazy :(