Would a dash between two dates be correct when you want to denote "through" the last date noted? If the period of time is only up to the last date, would you then use the word "to?" Thanks.
A dash has no special meaning one way or the other.
If there is some confusion, you must specify in writing. I think most people would interpret "Offer good from Jan 3-Jan 10" to mean the offer is still good on the 10th. Saying "through Jan 10" makes it explicit, but saying "to Jan 10" does not necessarily exclude the 10th.