Setting the final retail price including tax over the object model

[sfhbsf]

Hello!

 

Im trying to set the price of a product programmatically in my module.

$object->price = $aP[list_price];
$object->id_tax_rules_group = $iTaxClass;
$object->tax_name = $sTaxName;
$object->tax_rate = $iTaxRate;

When I do this, the price that I enter which is the final retail price including taxes is shown as "pre-tax retail price", tax is added, in the end the price is wrong. What I need to do that I am able to enter the "After-tax retail price"?

 

Thanks