After checking out the camera that you've suggested - personally I'd go with both.
Why?
Because if that one camera dies... you've got to go out and grab another... all the while you're shop & staff are vulnerable.
To be frank, if you're looking at spending that kind of money on one camera... I'd rather spend a few quid more and go with the Mobotix 360 degree MX-Q24M - Fully digital images caught, plus... you can also choose quad mode and view from 4 different angles with the one camera.
Take a look at this short video clip of your AXIS M3007
http://www.axis.com/products/cam_m3007pv/video/
Then look at this...
http://www.youtube.com/watch?v=ChqWds5BkLY
10x better quality camera.
If you've already got some cameras in the shop installed why not just buy one of the new DVR's average cost - roughly £200 or you can get a dirt cheap one off Ebay, but expect to have no warranty, even if it comes with one... trust me they don't... What exactly can a lil chap in China do for you in the UK when your DVR dies, and the re-sellers here in the UK don't give two monkeys about you or your system to be frank.
Grab one of the Mobotix Cameras and install all onto your new DVR.
Positioning of cameras is a choice that only you can make really.
Personally, I'd have a camera on the entrance - the till - blind spots
Then install the Mobotix central on the back wall facing the entrance - remember, you can zoom in with this one camera, and when I say zoom in... I mean zoom in! We had a demonstration of the Mobotix 360 degree camera, the room was roughly the size of half a football field, and the engineer zoomed in on the light switch at the far end of the room!
Quality gear TBH - and for what you're buying, relatively cheap too.
Cheapest I've actually found it for is about £750 + VAT - When these came out they originally they were about £1000 each
Just found it on ebay for £650 with a starting bid of £450 - if you're happy to purchase of Ebay go for it, if not pay the lil extra and get a qualified engineer to install it for you too.
http://www.ebay.co.uk/itm/Mobotix-Q...ther_Computing_Networking&hash=item2ec7e888fd