In Analysis Services, when designing your cube in BIDS, under the Calculations tab you can create calculated values by using Calculated Members. If your calculation happens to be a currency type, you would be happy to find that under the Format string drop-down there is a “Currency” option. However, in my experience this doesn’t actually format the value as you would expect. To show your value with dollar signs, and comma’s you can put in this value instead:
(include the double quotes)
“$#,##0.00;($#,##0.00)”