Played this card game a couple years ago while backpacking in South America with some Germans (I think).
There was a betting system, but we didn't use any chips or currency, etc. It had a somewhat similar strategic angle like poker, but was less reliant on chance or bluffing and more reliant on statistics and probability.
Basically you could bet 'knocks' (like, knocking on the table) - and you had 21 knocks and if you were more confident in your hand, you could bet additional knocks. If you hit 21 (or ran out, starting at 21, I can't remember), you lost. You had some cards out in the middle, but some in your own hand.
I wish I remembered more about the scoring of how you won hands but it was a long time ago...