NBA: How much is half a point worth?

[slapdash]

Suppose one bookie is offering a team at +10.5 at odds of 1.90, and another is offering it at +10. How much higher would the second bookie's odds have to be before it's worth accepting the lower handicap? 1.95? 2.00? This clearly depends on the probability of the team losing by precisely 10 points. Do any of you experts have a rule of thumb about how likely this is? And does it depend significantly on the line? If the handicap is small (only +2, say) then I imagine it's a little more likely that the team precisely covers the spread, if only because a tie followed by a 2 point loss in overtime is more likely than a tie followed by a 10 point loss in overtime, but is this a significant difference?

[TazaD]

Re: NBA: How much is half a point worth? In US terms, a team is say -3 (-110) [which is 1.91....ie. 100/110], you would be able to buy 1/2, get -2.5 for (-120) [which is 1.83...ie. 100/120]. I know SportingBet have a sliding scale you can check out, and I think Bet365 might too.