My dog started sneezing on Monday, its not all the time but alot more than usual has anyone got any ideas?  He is fine other than this.

One of mine also was sneezing about 3 weeks ago and it lasted about 5days. Prior to that the other one of mine sneezed for about 3 days and just stopped.
when I asked the vet. nurse at our surgery if it could have been kennel cough, she said yes more than likely. They don't actually always cough, they can sneeze and make that gagging sound as if they have caught their breath. I believe its called 'reverse sneezing'.
So it sound like yours could have a bout of kennel cough also.
I kept mine in and warm, and as she was feeding ok I didn't worry too much. Apparantly Benylin cough syrup helps if the coughing starts.
Hope this has been some help. It does sound as if there is a lot of KC going around.