I've found the rates escalating in recent times. Previously no tipping was ever required, in my second home of bombay at least, but these days 10-20% at restaurants and rounding up significantly when paying taxis and autos is becoming the norm.

In North India, i would give 10% at restaurants for excellent service only and only ever round up cab fares for exceptional friendliness, honesty, etc.

As for other tourism services, i would only tip someone for carrying my bags a long way or providing useful honest advice.