Recalculate order grand total including discount and tax

Question

I have an order data without shipping included, i tried to re-calculate total order when adding shipping price like this:

$shippingAmount = '30000';
$quote = $this->getQuote();
$quote->setGrandTotal($quote->getGrandTotal() + $shippingAmount);

but the above code won't recalculate total discount and tax

Answer 1

Once you set the Shipping method, you should tell magento to Collect Totals again. Refer below code:

$onepage = Mage::getSingleton('checkout/type_onepage');
$quote = $onepage->getQuote();
$shippingMethod = 'shipping_method_code';
$onepage->saveShippingMethod($shippingMethod);
$onepage->getQuote()->collectTotals()->save();

The above code will work if you have a shipping method with code 'shipping_method_code' for the shipping address you selected. Read the tutorial to learn how to create a shipping method Here or use any existing shipping methods like USPS, UPS, Flat Rate etc.