yes you can sit for scwcd 5.0 because voucher is not for specific exam.You can use the same voucher for scwcd or your friend can use the same voucher for
scjp exam.It means you can take any valid exam.On voucher ,only mentioned is that something look like: cx -0xx the last xx means you can take any exam whether it is 55(for scjp) or 81(scwcd 1.4) or 83 for scwcd1.5.but sun has declared some date after which you can not take scwcd1.4.But you can go for scwcd5.0.
I thinks it will help you
Please anybody correct me if i am saying wrong.