If a fee needs to be paid to use a road or to pass a gate you can use the tag toll=yes.

In this example, does everybody need to be pay the fee including residents of Tierra Benita? Or is this more of a bribe for the guard to let vehicles without sticker pass through?

By the way, is there a road connection at https://www.openstreetmap.org/node/8318434630 ? On aerial imagery i looks like there is no proper connection, or maybe only passable on foot/bicycle.