Look at Ask Amount Rule Code Entry for the ask amount in question. The base field is the name of the calc field used for the ask amounts. If you look up the calc field in Calculated Field Entry you can see the function it calls in the expression field.
Once the base amount is calculated, TA will return the ask amounts for the bucket it fits into. Buckets are delineated by the From and To Amounts.
Make sure you have set a Round Amount of at least $.01 on Ask Amount Rule Code Entry, otherwise some amounts can fall between buckets. For example, if round amount is not set, 9.996 will not fall into the 9.99 or less bucket nor the 10.00+ bucket.