I have to calculate total tax based on a graduated scale. Let's say I make
$15,000 (in cell A1) and I want to calculate tax in one cell (in cell B1).
The tax rate is such that the first $1,000 is at 0%, the next $2,000 at 10%,
the next $3,000 at 20%, and then anything higher than $6,000 at 25%.

What would the formula look like in cell B1 to calculate the tax expense of
$3,050.

Thanks,
Scott