I would charge exactly those dates for a "holiday" rate. You need to look at when the holiday falls ie: if the 4th is on a Monday, I would start the holiday rate on Friday night and end on Tuesday night. If the holiday is on Wednesday, I would charge the 2 days before and 2 days after.
Every area is different, so you might want to check similar listings to yours on VRBO or Homeaway (wherever your property is listed) to see how they handle holiday periods. For example, I know owners in my area who charge a 3 night minimum holiday rate for some holidays (like MLK, Memorial and Labor Day) but 5 night minimum holiday rate for Thanksgiving, Christmas and New Year's. I personally charge 3 nights at the holiday rate for July 4th but you may want to set 4 or 5 nights because that's more the standard for your area. And like Sophie suggested, our holiday rate dates float from year to year, depending on where the holiday falls.