as far as I have learned the prizes are not only named in Euros but usually in Rupees. To make it more comfortable for tourists (and lots of them in Mauritius are from Europe) it is a kind of hospitality to work out the figures in Euros. Many touristic places around the world make use of this kind of "service".
Due to VAT, you have the same system e.g. in Great Britain and U.S.A. Often prizes are namend without VAT and it is mentioned that they are without. As VAT is a fixed rate, the total amount of a certain item you are interested in is fixed as well. You only need to add the official percentage to the official prize. In the end there is no "surprise" about the rate.