Hi there. I'm trying to create a tiered commission structure calculator, but can't figure out how to make the formula work. I think it should be pretty simple (darn my weak excel skills):

<$500 = 5%
$501-$1000 = 8%
$1000-$1500 = 10%
>$1500 = 12%

For example, total sales of $1800 would generate $151 of commission based on:
(First $500 * 5%)+(Next $500* 8%)+ (Next $500* 10%)+ (Final $300* 12)

Any help is much appreciated!