Place 3 lime slices in single layer on small plate. Pour enough salt on another small plate to reach depth of 1/4 inch. Lightly press rims of 2 Margarita glasses onto lime slices, twisting to extract juices and coat rims. Dip moistened rims into salt to coat lightly.
Combine ice cubes, tequila, triple sec, and lime juice in cocktail shaker. Shake until outside of shaker becomes frosty. Strain mixture into prepared glasses. Garnish rims with 2 remaining lime slices and serve immediately.
