Brahm it might help to understand what part of the retail solution you are working on. "In-store" systems are generally known as Store Systems. That would include your point-of-sale (cash registers), store inventory, payment solutions, floor planning (planograms), loyalty solutions, kiosks and related facilities management systems.
Depending on the size of the retailer and the sub-industry (e.g., grocer vs. luxury brands) you might deal with different parts of IT or even the business. These systems are not changed often or without heavy scrutiny since there is usually a large investment and long history of data that goes with them. If your product compliments or enhances one of them, it may be an easier sell.
This is a good time for vendors looking to sell into Retail since many systems are in the process of being replaced, in the stores, with more modern technology. Small Retailers are easiest to convince but you'll need to make a lot more sales calls. Large Retailers will be most difficult but one of the majors could be a game changer for your company.
I've worked extensively with Retailers in North America, Europe and some in Asia. Feel free to ping me off list if there are specifics you'd like to discuss.