Cape Verde is quite a poor country. The women and girls work hard to earn a living. Most of business, restaurants, retail outlets are owned by foreigners and they employ local labour, usually Capo Verdian local girls (they work for fresh air).

The other minor race are the Senegalise who usually dont work for anyone, but sell their African arts, so when you go to a resturant you will almost certainly be served by a Capo Verdian girl. Usually in restaurants they accumulate the tips and it is shared out. The amount will always be what you think is fitting for the service you have recieved . Please do not compare this with the country that you have come from. Usually when you pay,  the change is in ESCUDOS the local currency. The change really does add up to alot, may be a couple of euros. 

Appreciate what good service you recieve but don't feel forced to giving generous tips for bad service.