Patrick,
we are a small community museum in Ontario, and would
have no use or desire to use a turnstile,

we use numbered tickets, and when we ring in an admission
to our cash register, it tells us how many adults, kids,
whatever were rung in, which can be double-checked with
our side of the ticket we provide to the visitor, and
voila - a balance!

The only way to skew it is if a staff member/volunteer
chooses to put extra money in the till for some reason?

Good luck
tracy marsh