the mandatory 5% (employer and employee)must be kept in the a/c until you retired, go overseas.....
the rest, depends on your years of service: 1 yr = 10% .....10 yrs = 100% will be given to you when you leave the company or you may elect to keep in the a/c
you said your co. paid 10% each mth (5% mandatory and 5% voluntary) and your contribution is 5% each mth. the co.'s 5% mandatory and your own contribution 5% needs to stay in the a/c.
the 5% voluntary contribution from your co., you could get the cash or remain in the a/c and the amt depends on years of service. since you worked >10 yrs, you can get back all the 5% voluntary contribution either in cash or keep in the a/c.