Modify product price based on price with tax included - php

Question

I'm building a Woocommerce store and I need to get all the prices with tax included to end in zero (For example, if the original price with tax included is 1234, then I round it to 1240).
Products are imported to my website in bulk (+2800 products) but they have the price without tax. I configured the tax in woocommerce settings and I display prices with tax included in the store.
To fix the "ending in 0" problem, I created a method to change the tax value so the final price ends in 0:
// Calculate tax
function filter_woocommerce_calc_tax( $taxes, $price, $rates, $price_includes_tax, $suppress_rounding ) {
$key = array_search('IVA', array_column_keys($rates, 'label')); // find tax with label "IVA"
$tax = $taxes[$key]; // get the current tax
$subtotal = $price + $tax; // get the total
$final = ceil($subtotal / 10) * 10; // modify the total so it ends in 0
$new_tax = $final - $price; // calculate new tax price
$taxes[$key] = $new_tax; // update tax in array
return $taxes; // return new calculated taxes
};
add_filter( 'woocommerce_calc_tax', 'filter_woocommerce_calc_tax', 10, 5 );
It works really good, but I figured that if I change the tax price, I'm actually changing the tax rate (%) and I can't do that for legal reasons.
That's why I wanted to change the price of the product without tax instead.
I can use the same method:
$final = ceil($subtotal / 10) * 10; // modify the total so it ends in 0
$new_price = $final - $tax; // new price without tax
But I don't know what hook to use to achieve this.
Is is possible to change the price with hooks and filters?

Answer 1

I finally got a solution, first I created a method to calculate the prices without tax:
function get_net_sales_price($price, $tax_rate = 0) {
$subtotal = $price + (1+$tax_rate);
$final = ceil($subtotal / 10) * 10;
$new_price = $final / (1+$tax_rate);
return $new_price;
}
Then I got the taxes based on the product and customer location (thanks to this answer):
function get_tax_rates($product) {
// Get an instance of the WC_Tax object
$tax_obj = new WC_Tax();
// Get the tax data from customer location and product tax class
return $tax_obj->find_rates(array(
'country' => WC()->customer->get_shipping_country() ? WC()->customer->get_shipping_country() : WC()->customer->get_billing_country(),
'state' => WC()->customer->get_shipping_state() ? WC()->customer->get_shipping_state() : WC()->customer->get_billing_state(),
'city' => WC()->customer->get_shipping_city() ? WC()->customer->get_shipping_city() : WC()->customer->get_billing_city(),
'postcode' => WC()->customer->get_shipping_city() ? WC()->customer->get_shipping_city() : WC()->customer->get_billing_city(),
'tax_class' => $product->get_tax_class()
));
}
And finally I use a hook to return the correct price for the product (woocommerce then adds the tax when needed):
function filter_woocommerce_price($price, $product) {
$rates = get_tax_rates($product);
// Finally we get the tax rate and calculare net sales price:
if( ! empty($rates) ) {
$key = array_search('IVA', array_column_keys($rates, 'label'));
return get_net_sales_price($price, $rates[$key]['rate'] / 100);
} else {
return get_net_sales_price($price);
}
}
add_filter('woocommerce_product_get_price', 'filter_woocommerce_price', 99, 2 );
add_filter('woocommerce_product_get_regular_price', 'filter_woocommerce_price', 99, 2 );
add_filter('woocommerce_product_variation_get_regular_price', 'filter_woocommerce_price', 99, 2 );
add_filter('woocommerce_product_variation_get_price', 'filter_woocommerce_price', 99, 2 );
Now I'm getting the right tax amount, and also all the product prices end in 0.