The exact details of what is large xlarge etc can be found at http://developer.android.com/guide/practices/screens_support.html but no, my nexus 7 is officially classed as xlarge as xlarge is 960x720 so it isn't possible to identify a ten inch tablet as ten inch like that.
However you could identify the resolution and dpi at runtime to load a tablet specific layout or add tablet specific variants to your current layout.
I am planning to include a tablet layout at a later stage in this app but only have had time to make a phone layout and that's why I want to limit only phone size screens to be able to download the app for now.
I then want to make a tablet layout and then allow people with tablets to buy the app. But for the mean time I only want people with phones for now to get the app and then at a later stage when I finish the tablet layout then allow people with tablets to be able to get the app.