vveocart shopping cartr customisation

The project is to customise vevocart multistore shopping cart. [login to view URL] currently we use this software to urun a number of stores. The standard software allows you to run multiple store and DISPLAY in multiple / different currencies per store i..e GBP, EURO, DOLLAR However when the customer checkouts and pays the currency is always exchanged back into the default currency set in the main store. we want to have a change - so that the customer can choose the currency he wishes to use and checkout / completes payment in the currency of his choice. It would need to function correctly with both paypal standard and paypal pro uk gateways. As these are the gateways we use. Paypal gateway allows to accept multiple currencies in one account. FYI - vevocart uses Paypal / Paypal PRO UK C# source code / DLL libraries IIS 5.1 or later. .NET Framework 4.0. Microsoft SQL Database MS SQL 2005/2008 all other functions in the standard software are fine -- and should remain as they are.