"Exclusive or" ouch - I was thinking exponential also.

Arguments expressing dismay that mixing numeric types provide incorrect results, hmmm, isn't that a big part of programming?

declare

@x money

set @x=9.99

set @x=@x+.00489999

Print @x --no change

set @x=9.999

Print @x --duh - 10

It's always about the math.