If you mean Photoshop v 5.0, no. It's no longer sold or supported.
If you mean Photoshop CS5, you would have to purchase CS6 Mac as a cross platform upgrade.
Yes sorry I did mean Photoshop CS5...thank you!:-)
You're welcome. This CS numbering has caused more than a few folks a bit of confusion, CS5 is also known as v. 12.