Hi,
What you want is an ERP system which will not only show you all sales and inventory collectively but show you detailed sales and purchases and inventory in the shops, yes i have already build an application basically an ERP a collection of applications which modular based and can be used for your business after modification.
We specialize in Designing Business applications, ERP, CRM, Goal Management, inventory tracking, employee tracking and payroll software.
We can deliver you an efficient bug free solution in minimum time possible, You can check our reviews of clients we already worked with :).
My Experience includes CRM for YZC company Singapore, ERP for electrical equipements installation and distribution company Pakistan (only distributor of General Electric in Pakistan), Hospital Management system and ERP for Sweets and bakery production Company.