In my local newspaper (News & Observer - Triangle, NC) today was an add that says you can purchase the following for only $.15 from 3-5pm Monday 6/15:

small hot coffee
3oz soft serve cone
donut
small iced coffee

The details state:

Celebrate the tremendous growth of Dunkin' Donuts and Baskin-Robbins. We've just opened our 15,000th store, located here in Raleigh. Stop by any of our stores for amazing 15-cent deals on America's favorite hot and iced coffee and delicious food.

I'm assuming based on this ad that any Dunkin' Donuts is participating. There was nothing I could find on their website, so you might want to call first.