What I suggest you do is, goto the MAC store & swatch the colors from NC25 through NC 27 on your jaw line. go outside to natural light & see which color blends to your exact skin color. You really can't judge in the store with the floresent lights.
The MA wanted to give me NC40 I said no way. I insisted on NC 27 & the color matches perfectly.
Also, when you swatch try to wait 10 min b/c the color can change on you depending on what skin type you have. (ex: if you have oily skin, the color can change to a darker color).
Hope this helps you