Yes
Sellers negotiate really good rates with DHL that are significantly cheaper than USPS. Just because it will be a pain for you to have your item go to Secaucus (that's where it was when I was dealing with them a bunch of years ago) will not make it worthwhile for a seller to create rules that certain zip codes get shipped USPS or whatever.
Though in all likelihood, you will get the item within the same time as USPS first class would get you the item, albeit with a higher risk the item will just get stuck in Secaucus without ever making its way to you.
As for the $5 shipping charge, they must have no competition and are charging you because they can.