Windsor Casino - 10% rake, 5$ max, at what limit is this even beatable

[DCWGaming]

When I visited Windsor half a year ago, me and a friend just screwed around and played 3/6 and 100NL. I lost 125$ canadian or something minor, and fairly recently I started to realize...I dont think their rake structure is even beatable.

I'm not too great with coming up with the equation to figure out the BB/100 that the rake takes away from you, but it seems like this would be enough to cripple everyone at the table.

At what limit would the game become beatable? I'm assuming 10/20...which is the highest limit they offered.