I have a worksheet with a column of values (policy numbers) and associated
amounts:

123 $10.00
456 $ 5.00
123 $20.00
789 $50.00
456 $15.00

Total $100.00

Under the body of these detail values, I would like to summarize the total
for each policy number and then show a grand total:

123 $30.00
456 $20.00
789 $50.00

Total $100.00

The policy number values could change from month-to-month, so I would like
to use some sort of formula to list all of the unique policy number values
and then put their corresponding totals in the next column.