Inventory, Sales, Retail Management System

Hello,

One of our customer is looking for a complete solution from managing Inventory to sales to retail management. On exploring I saw that microsoft has the Retail Management System (RMS) then CRM for Sales Management. Can someone guide / help me to understand what is the best solution from Microsoft to manage all 3 systems that customer is looking for?
I went through many resourses Retail Management Video for help but,did not find any help.
Please help me out.

Any help will be appreciated.
Thank you .