Changing rounding policy globally

Question

I am using Magento CE 1.8.1.0. I have a requirement to use ceil on all prices/fees. I am also using product custom options.

It seems that the rounding is not done in a single place. First I modify app\code\core\Mage\Core\Model\Store.php:

public function roundPrice($price)
{
    return ceil(sprintf('%.2f', $price));
}

public function formatPrice($price, $includeContainer = true)
{
    if ($this->getCurrentCurrency()) {
        $roundedPrice = $this->roundPrice($price);
        return $this->getCurrentCurrency()->format($roundedPrice, array(), $includeContainer);
    }
    return $this->roundPrice($price);
}

But since I am also using catalog price rules, the special price shown in the product page is not being ceil'ed. So I modified the following: app\design\frontend\base\default\template\customoptions\catalog-product-view-options.phtml:

return Math.ceil(prPrice);
...
return Math.ceil(totalOpPrice);

Since I have product custom options, there are discounts for the product as well as for the options. I realize that the unitPrice (product price + option prices) in the shopping cart is calculated without any rounding. In my test, the unitPrice is $399.2 + $63.2 = $462.4 and in the checkout cart, after the ceiling the unitPrice is shown as $463. However I want the behavior to be that the unitPrice is calculated as: $400 + $64 = $464.

It seems that the row total for each item is calculated without any ceiling. Where should I modify the logic that calculates the row total?

The other question is that it seems that roundPrice is done all over the place. What is the best approach if I just want to change the rounding policy globally?

Answer 1

It seems that if I change the following file app\code\core\Mage\CatalogRule\Model\Observer.php:

$key = "$date|$wId|$gId|$pId";
if (!isset($this->_rulePrices[$key])) {
    $rulePrice = Mage::getResourceModel('catalogrule/rule')
            ->getRulePrice($date, $wId, $gId, $pId);
    if ($rulePrice != 0) {
        $this->_rulePrices[$key] = Mage::app()->getStore($storeId)->roundPrice($rulePrice);
    }
    else {
        $this->_rulePrices[$key] = $rulePrice;
    }
    if ($this->_rulePrices[$key]!==false) {
        $finalPrice = min($product->getData('final_price'), $this->_rulePrices[$key]);
        $product->setFinalPrice(Mage::app()->getStore($storeId)->roundPrice($finalPrice));
    }
}

I can revert the changes in the above *.phtml and still get the correct unitPrice both in the product page and the checkout cart page.