Don't know about the voucher question.
There are many sample code questions in the exam : e.g. what will this EL expression evaluate to ? (Hope this does not break any rule).
Try the Jwebplus simulator. I found the questions strikingly similar to the real questions. (don't know about whizlabs or others).
-DM
SCJP 1.4, SCWCD 1.4, SCDJWS(beta)
[ October 22, 2008: Message edited by: DM ]