You want to join them like this:
select p.*, p.MarketValue * br.rate
from Performance p left outer join
BillingRates br
on p.MarketValue between br.[from] and br.[to]
This is called a non-equijoin. The performance on such joins is generally worse than on equi-joins. Having an index on [from], [to]
will help.
Also, you shouldn't use SQL reserved words as column names. That is, "from" and "to" are inconvenient names.
If there might not be a match, then you might want:
select p.*, p.MarketValue * coalesce(br.rate, 1.0)
so the result is not NULL
.