magento中的Paypal订单状态问题（INR到USD转换）

I am customized paypal module for INR currency

So I converted INR amount to USD amount for paypal transaction

Paypal payment is working properly.

Issue is order status changed to Suspected Fraud.

How to change return amount from paypal before order status change

Below code is amount conversion before paypal transaction

$currentCurrencyCode = Mage::app()->getStore()->getCurrentCurrencyCode();
        $result['amount'] = number_format(Mage::helper('directory')->currencyConvert($result['amount'], 'INR', 'USD'), 2);
        $result['tax'] = number_format(Mage::helper('directory')->currencyConvert($result['tax'], 'INR', 'USD'), 2);
        $result['shipping'] = number_format(Mage::helper('directory')->currencyConvert($result['shipping'], 'INR', 'USD'), 2);
        $result['discount_amount'] = number_format(Mage::helper('directory')->currencyConvert($result['discount_amount'], 'INR', 'USD'), 2);
        $result['discount_amount_cart'] = number_format(Mage::helper('directory')->currencyConvert($result['discount_amount_cart'], 'INR', 'USD'), 2);

Please suugest any solution to fix this issue.

Thanks in advance