Changing product prices smaller than $5 to the price of $5 in function.php (from $4.49 to $5): now tax is still calculated from $4.49 but need from $5

Question

I am trying to programmatically change the pricing of my WooCommerce products from $4.49 to $5. It works nice.

While the product price is nicely visibly everywhere as $5, there is now an issue with tax calculation, as it continues to be computed based on the original price (e.g., $4.49) rather than the updated $5.

Example:

Cart total is $10 from 2 products that are each $5.

But tax of 19% shown is as $1,60 because it is still calculated based on the $4,49 original price. Goal would be to have the 19% tax calculated on the changed prices that would be $1,90 from the $10 in this example.

The objective is to resolve this inconsistency and ensure that the tax is accurately calculated from the new fixed price of $5 for products falling below the $5 threshold.

This is my code that I currently use in function.php:

/* Changing the price of WordPress products dynamically by redpishi.com */
function filtering_product_prices( $price, $product ) {
$price = (float)$price;
$new_price = $price * 1 ;   // New price formula
    
// paste conditional codes here
if ( $price < 5 ) {  
return 5;  
} 
return ceil($new_price);
}

function custom_price( $price, $product ) {
    wc_delete_product_transients($product->get_id());
    return filtering_product_prices( $price, $product );
}
function custom_variation_price( $price, $variation, $product ) {    
    wc_delete_product_transients($variation->get_id());
    return filtering_product_prices( $price, $product );    
}

add_filter('woocommerce_product_get_price', 'custom_price', 90, 2 );
add_filter('woocommerce_product_get_tax_price', 'custom_price', 90, 2 );

// add_filter('woocommerce_product_get_regular_price', 'custom_price', 90, 2 );
// add_filter('woocommerce_product_variation_get_regular_price', 'custom_price', 99, 2 );
// add_filter('woocommerce_product_variation_get_price', 'custom_price' , 99, 2 );
// add_filter('woocommerce_variation_prices_price', 'custom_variation_price', 99, 3 );
// add_filter('woocommerce_variation_prices_regular_price', 'custom_variation_price', 99, 3 );

Tax is calculated with Germanized Pro plugin.

Any hero out that that can help me to get tax calculated right for the above code?

Thank you already very much!

Answer 1

I don't think it's a good idea to "overwrite" prices like that on the front end only. You could use woocommerce_before_calculate_totals hook to recalculate everything during checkout, but I suspect there might be other places where the old price below $5 will persist, especially while using plugin like Germanized Pro.

I don't know your specific case but if you don't actually need the old prices for some future use I would suggest simply batch editing products on Woocommerce admin. If for some reason sorting them by price is problematic you can use more advanced solution like Bulk Table Editor.