Day 3 - Thinking about Gratuity in South Africa

Day 3 - South Africa uses Rand as their official currency.  So upon our arrival to South Africa, we had to exchange dollars for Rand. The Rand to dollar is current 15 to 1.  Nelson Mandela is on the R10, R50, and R100, all the bills we've seen so far! They actually have coins that are in R1, R2, and R5. So now that we have the money, we're wondering, how in the world are we supposed to tip? It looks like here there is a 10% minimum tip that you can give as opposed to the US standard 15 to 20 percent, while at a restaurant. The porter who helps you with your bags gets about R15, and a cap driver can get up to R10, depending. . .  Interesting.  Tiffany & Kennard