Pat chicken breasts dry with paper towels and place on a baking sheet. In a small bowl, combine cumin, paprika, chili powder, salt, pepper, and sugar. Rub spice mixture all over both sides of chicken. Set aside for a moment.
In a small bowl, combine tomato, jalapeno, lime juice, cilantro, and salt and pepper to taste. Place in refrigerator to chill.
Preheat a grill to medium-high. Once grill is heated, grill chicken, turning once until meat registers 165F, about 10-12 minutes.
Serve chicken warm with chilled salsa on top. Enjoy!