You can exclude items with specific values, such as credit amounts, from selection. Many sampling approaches recognize that monetary unit sampling can test for only overstatement and because of this, they exclude items that reduce the value being tested. To do this, you can specify a test such as:
IF AMOUNT>0.
Note: If you use a condition to restrict the items to be sampled, you effectively reduce the size of the population. A sampling method that relies on the size of the population must be adjusted accordingly.