Bachelor of Accounting Sciences degree would be the correct way to say this. Lower case 'd'.
Other Examples:
- John received his Bachelor of Accounting Sciences degree this May.
- ABC Inc., is seeking a candidate with a Bachelor of Accounting Sciences degree.
- ABC Inc., is seeking a candidate with a bachelors degree in Accounting Sciences.
(Edit) Depending on what country you're utilizing or descrbing this degree in, I would also look up similar degree programs and find out how it's described. Not all places use the same terminology.
Hope this help,
M