I Agree
Gringo tax is a good word for it. For those of us who have lived and experienced this daily, it is a fact of life for Gringos in the DR. The problem with many businesses in my area, Rio San Juan and the North Coast in general, is that there are no prices on most things like clothing, shoes, fans, etc...(outside the supermarkets). So, the general rule of thumb is to send the wife (Dominican) in to check on how much it cost before I show my white skin. This works only the first time because after that they know she is married to a Gringo and will quote her a higher price the next time, which she usually ends up arguing over because she knows it should be cheaper.
If I go in alone the price will usually depend on two things: 1) I'm a gringo so I know, and expect it to be quoted at a higher price, 2) Percentage increase will also depend on your level of Spanish language skills and letting them know you live there and are aware of the market value of the item. Sometime I might throw in a, "Yo vivo aqu?, dame el precio Dominicano".
Again, like many here there are many places that don't do this but when it comes to pricing things in the DR, for a Gringo, it's definitely an art form. I can't say how many times I've argued over a quoted price that was suddenly higher when the job was done, or getting ready to be started. Perfect example, how much for a inversor, batteries and installation? 25,000 pesos. After the job, here's 25,000 pesos. No, it's 26,500. You told me 25,000. Yes but that didn't include the cables I had to buy. And the argument continues.........