The short answer is no, the Tangiers is not a real casino. It was actually the name of the fictitious casino (based on the actual Stardust) run by Robert De Niro in the movie Casino, and "CSI" has apparently borrowed the name as a good way to avoid identifying a real Las Vegas casino (in the same way that the series "Las Vegas" is set in the fictional Montecito casino).
The only real Tangiers that we know of in Las Vegas is the Tangiers Tower at the Sahara hotel, which is the newest of the three hotel towers there (the other two being the Tunis and Alexandria) and the only one where the rooms are equipped with individual thermostats, we were informed by the front desk. There’s also an online casino called the Tangiers.
Although there’s no real bricks-and-mortar property called the Tangiers, you can purchase novelty Tangiers playing cards and chips, inspired by the movie, for home use. Weighing in at almost 16 grams each, the full-metal poker chips are the heaviest on the market. Fashioned from solid brass, they have a diameter of 39mm and are available in $1, $5, $10, $25, $100, and $500 denominations from many sites, including www.oldvegaschips.com, which kindly supplied the photographs below. The chip on the left is a clay-composite prop chip from the actual movie and is much harder to come by than the brass ones.
Photographs © Steve Rizzo, Old Vegas Chips