Is this data in a number field?
Replace Field Contents can modify a specified field for every field in your current found set--which can be all records in your table and a calculaiton can be used to do the modification so the resulting value in the field can be different in each record and determined by the data present in your current field.
Ceiling can be used to round up fractional portions. Ceiling ( 1/3 ) returns 1 for example.
Thus, you can use an expression such as Ceiling ( YourTable::Field / 2 ) with the Calculaiton option available in Replace Field Contents.