Is it safe to mail an iPhone 5 domestically?

My sister got me an iphone 5 back east so that I don't have to pay the much higher sales tax here in California. My current iphone 4 is out of service because when she got the upgrade, my phone was deactivated. My sister offered to send me the iPhone via USPS and I was wondering if this is safe. I will be going to the East coast in 4 weeks to visit her anyways but the sooner I have the iphone the better. I was wondering if I should take my sisters offer and have her send it to me and should it be insured.
Responses appreciated

I would say it is safe as long as the iPhone won't be loose in the box, use bubble wrap (or something else like newspaper maybe) write fragile on the box… It should be fine then! Enjoy the new iPhone 5!

If it's being sent via USPS, yes it's safe.
I've gotten packages from relatives who live on the other side of the world safe and sound.
Plus you'll be able to track the package, so you'll know exactly the path it's going through.

USPS is very safe… But not guaranteed… Unless you buy insurance.
Looks like it would be about $15 total ($9.50 for $650 of insurance, $5.35 for USPS Priority Mail small box).
Like the others have said… Have her pack it well!