In some cases I can understand its a way of verifying employment, however as far as salary negotiations, i'm told it's basically poker, and if you show first, they are in charge.
not if your current number is way above market. it's also not at all like poker in that lying is not an advisable way to try to win. (never lie about salary, or anything else, to a prospective employer.)
You should tell them your total comp including benefits. Don't overlook the value of benefits.
At my last job for every hour I worked over my standard 40 hours I got an extra hour of annual leave. Standard hours in my field tends to be at least 45/wk so when I switched jobs I quoted a figure that included the value of this extra leave.
