I've seen a variation on this working at a number of US festivals - tickets rather than tokens -particularly when held at large fairground venues, used for both food and drink. Usually it's $1/ticket and then the portions of food or drink are scaled to whatever number of tickets.

I'm sure this makes more money in rounding up all the prices, but it does indeed make for shorter lines. Besides, these days trying to get the people who work the low paying food service jobs to make change? Get serious. Without a digital register to tell them what the change is they can't cope! Being haned the exact number of tickts works for even the dimmest bulb of a server.

Joanne in Cleveland (with one Irish fest ticket left in my pocket...)