Currently Farm Fund$ can calculate State Tax withholdings using either a flat tax rate, a percent of the federal taxes, or a graduated rate.
What you are describing sure sounds like a graduated rate structure. With this method you will enter dollar ranges of wages (annualized) and enter a tax rate for each range. For example: If the first $10,000 is taxed at 1% and the next $10,000 at 2% and everything over $20,000 is at 3% you would enter:
0 - 10,000 1% 10,001 - 20,000 2% 20,000 - 0 3%
All tax methods allow you to enter an exemption amount which is an annual amount that is multiplied by the number of exemptions claimed by each employee. This amount is subtracted from taxable wages in calculating withholdings.
I hope this helps. Let me know if you have any further questions.