Conditional formatting to test for variance

Hi,

I'm trying to test for variance using conditional formatting. Example attached.

The problem I'm having is that excel highlights any variance, whereas I don't care about really small variances. In row 3 for example, as long as the numbers would round to 500, I don't care. The numbers are variable and will change on a monthly basis. It might be 500 this month, but 300 next month, and I'm having trouble writing a formula that will limit the highlighting to situations where the rounded total would be different.

Thanks.

There's only 3 values in each row, so st.dev won't have much impact.