Kdjykuj

I saw there are some post like this but I tried that answer and dit not work.

I am learning how to use magento, and What I wan to try is remove all the tax from the cliente when them have add 3 products to the cart.

I am using an observer event. And the function it run is:

Here is the config.xml

<events>

  <checkout_cart_add_product_complete> <!-- identifier of the event we want to catch -->

    <observers>

      <checkout_cart_add_product_complete_handler> <!-- identifier of the event handler -->

        <type>model</type> <!-- class method call type; valid are model, object and singleton -->

        <class>descuentoiva/observer</class> <!-- observers class alias -->

        <method>addCheckout</method>  <!-- observer's method to be called -->

        <args></args> <!-- additional arguments passed to observer -->

      </checkout_cart_add_product_complete_handler>

    </observers>

  </checkout_cart_add_product_complete>

<events>

And this is my actual code for the fuction:

public function addCheckout(Varien_Event_Observer $observer)

        {

            $cart = Mage::getModel('checkout/cart')->getQuote();                

            if (count($cart->getAllItems()) >= 3) {

                $products = $cart->getAllVisibleItems();

                foreach($products as $item) {

                    echo $item->getPriceInclTax()."<br>";                           

                    if ($item->getTaxAmount() > 0) { 

                        $item->setTaxPercent(0);

                        $item->setTaxAmount(0);

                        $item->setBaseTaxAmount(0);

                        $item->save();  

                    }

                }

            $cart->save();              

            }               

            #die("patata"); 

        }

But when I look the checkout it did not work.

You also have to config your event in config.xml. Learn here

Now, we need to use this event checkout_cart_product_add_after and checkout_cart_product_update_after.

In your config.xml

<global>

  ..

  ..

  <events>

    <checkout_cart_product_add_after>

      <observers>

        <my_module_product_add_after>

          <type>singleton</type>

          <class>modulename/observer</class>

          <method>checkout_cart_product_add_after</method>

        </my_module_product_add_after>

      </observers>

    </checkout_cart_product_add_after>

  </events>

  ..

  ..

</global>

Now function checkout_cart_product_add_after() in model/observer.php

public function checkout_cart_product_add_after(Varien_Event_Observer $observer)

    {

        $quote = $observer->getEvent()->getQuote();                

        if (count($quote->getAllItems()) >= 3) {

            $items = $quote->getAllVisibleItems();

            foreach($items as $item) {

                $item

                   ->setTaxAmount(0)

                   ->setBaseTaxAmount(0)

                   ->save();

            }               

        }               

        Mage::log('my log', null, 'my-log.log'); //creates log file if this function is called 

    }

This will set tax to 0 for all items that are in cart. You would want to check sales_flat_quote_item table.

Because you would also want to check this event on item update on cart, so you have to set another event for this checkout_cart_product_update_after.

you can call same function for this event too.

I haven't tested, but this should work.