Price Break - Boundary conditions

 Hi all,

If I have a quantity based price break as follows (in the price list)

Units Ordered                     Price

0 - 50                                   $100

50-100                                 $90

Which price applies if I order 50 units? $100 or $90? Are there any variables or settings that can influence which price gets selected?

Is there a way to set up the price breaks that do not start from zero? 

Example:   10 - 100  ---- Price $100

                100 - 200     ---- Price $90

And ranges that do not overlap, example:

0 - 50  Price $100

51 - 100 Price $90

Thanks in advance for your responses.

Nat.