I see that you are using a calculated field (Converted Sales) to convert your Sales measure into the format you want it. You do not need that calculated field, you just need to format Sales appropriately.
- Right Click on Sales under Measures, select Default Properties, and choose Number Format
- Click Currency (Custom). Set the decimals places and negative values however you want.
- Under Display Units, choose Thousands (K).
- Below that, check the box that says "Include thousands separators.
- Now click on Custom to the left. The field listed as Format should show the following (or something similar): "$"#,##0,.00K;("$"#,##0,.00K)
- Change the K's to M's.
- Click OK
Doing this will show your Sales with commas separating the thousands and in thousands using M instead of K.