In every situation then one radio are checked 'true' you can call an optional callback method.
JQuery is required.
radioWithCallback(eventElement,callback);
With test parameter
radioWithCallback("input[name='currency']");
radioWithCallback("input[name='currency']", function(){
alert("Hi");
}
);
radioWithCallback(".currency");
radioWithCallback(".currency", function(){
alert("Hi");
}
);