Some companies are used to an outdated belief that minimal information should leave the house. This is partly for business security but mostly reflect an assumption that it is possible to get better pricing if the size of operations is kept in secret.
The truth is that contemporary business environment has so much information floating around that it is not possible to hide how your main operations are organized. If your competitor wants to know, they know already. Provide your possible software partners with sufficient information, so they can offer you the best-suited solution they have.
Also, it does not pay off to give the impression that the scope of services needed is thinner than it is. Most of the retail software provides favorable conditions to bigger clients, so you will get a better deal the larger the operations are. Adopting a win/lose negotiation strategy, denying requests for critical project information like business drivers and budget expectations, and not providing access to the leadership team leads to the increased project and financial risk.
A retail software vendor is your partner who contributes to the backbone processes of your company. The idea of cooperation is growth and prosperity for both parties so that both the vendor and the software buyer can achieve the best results in their scope of conduct.