Tax tables are the basis for any payroll system. Zimra sets the tax tables to be used each year on the payroll system and notes how these are to be calculated to get the tax.
The basic equation for the Tax Table is
Amount Earned*Tax%-Amount
Hence if you are earning $10,000 per month
Using the 2019 example your tax lies in the 30% bracket and the amount to be deducted is $395; hence the equation becomes
(10,000*30%)-$395=$2,605