The simple answer is No, do not tip your tour guide.
When arranging a tour with a guide, it is always advisable to establish the fee in advance, and factor in an extra 10% that you will probably be charged as the service fee. Beyond this, tips are generally not necessarily expected by the more legitimate and professional tour operators, but this changes as you move down the scale.
You may be approached by locals willing to show you around markets, temples and other places of interest, and it is customary to give these people a small tip of no more than Rs 500. Exercise caution with these individuals, and do not be afraid to politely refuse unsolicited services you are not interested in.