Sugar in Indian curries? I've seen that sugar is used to balance out other flavors in a dish. I was just wondering if I could add a little sugar to a spicy curry(chicken curry, for example). Would that take away the authentic flavor? If no, then how much can be safely added before it becomes too sweet?
There is nothing inauthentic about using sugar in an Indian dish, even a savory one.  For example, Gujarati cooks often add raw sugar (jaggery) to daal and curries. Quoth Wikipedia:

"It is common to add a little sugar or jaggery to some of the sabzi/shaak and daal. The sweet flavour of these dishes is believed to neutralize the slightly salty taste of the water."

And here's an example Gujarati potato curry recipe, which includes a tablespoon of sugar.

As for how much to add, that's a matter of your taste and the level of acidity and/or saltiness in the dish.  My Gujarati friends in Boston like stuff rather sweeter than I would personally prefer, so be cautious.