I need some assistance in calling up record after processing records in a formula:

I have one table where production of something is recorded. there is a field called G/Unit which is a measurement of production performance. The staff get paid according to this field.

I thus have another table (payTable) with a field G/Unit which ranges in step of 0.25 (from 1 to 10.5) and a field for each product and the pay according to g/unit example:

g/unit product1 product2 product3
1 5c 7c 6c
1.25 10c 14c 8c
1.5 15c 21c 10c
1.75 20c 28c 12c
.
.
.

The two tables are linked. I first group by shift then group2 per product then i summarise(avg) G/Unit. this average is not always exact as the g/unit records in the pay table. i therefore only get the pay when the avg is the same as the records in the pay table.

how do i call the records from the pay table which are not exact as the G/Unit field in the payTable?