Customising WP E commerce plugin so as to get USD prices converted into INR at checkout

My client has a Wordpress online shop with WP E commerce plugin powering the back-end. He wants to sell in India and abroad. The following features are necessary for the same. 1. The shop will have a drop down to select options. (Like fab india web site) a) Delivery within India b) International Delivery 2. According to the selection the price is shown in INR (Delivery withing India) or in USD (International Delivery) - (International price will be added from the back end) 3. If the International Delivery is selected, the prices in the checkout page will be the USD price converted into INR (example the user from abroad adds a product worth $10 into the shopping cart. When he checks out it should show INR 538 - the converted amount) You can use Google API for the conversion. We have tried a currency converter plugin and it didn't do this job. However, if you think it can done by an existing plugin, let us know that too. The site uses Wordpress 3.4 and the WP E Commerce 3.8 *IMPORTANT* Ideally the output should be a plugin and you have to show us it working on a test site. If you don't have a test site, we will have to test the plugin ourselves before making any payments. If you have any workable suggestion (like tweaking the custom theme files) please let us know that too. Do not bid if you are not comfortable working with WP E commerce plugin. ONLY serious bidders please, time is precious for all of us. If you are ready to do this job, write the version of our WP E Commerce plugin in your bid message.