Set Default Currency

function setDefaultCurrency() {
var lookup = new Array();
lookup[0] = new Object();
lookup[0].id = '{0929D216-DDE7-E311-93EF-74D43599CE45}';  // your currency ID
lookup[0].name = 'Rupee';// Your currency name
lookup[0].entityType = 'transactioncurrency';
Xrm.Page.getAttribute('transactioncurrencyid').setValue(lookup);
}