Currency Formatting adding junk decimals

The currency format if done for more than 6 decimal places is adding junk decimals in the end.

e.g.

try this

var number = 8888888888.67;

console.log(parseFloat(number));

console.log(Ext.util.Format.currency(parseFloat(number), "",10));

this gives the output as - $8,888,888,888.6700000763

let me know how can i format the numbers till 10 decimal digit precision without modifying the contents of the number.