Using work perks, not just for discounts on what your company actually sells, all adds up. Even if you are in some select stores, sometimes just asking "is there a corporate discount?" or "do you do any deals for people working for this or that company?" will work and get you a free cookie, 10% off, or more. My favorite way of wording a discount question is using "family and friends of.."
**It is very important to note that for anything below, always ask and do it properly through/with work, not just taking something or charging back to the company. This is a no-brainer, but just in case... thought to mention it.
Personally, I've used the "proximity" question at stores (I work across the street, any discount for me if I buy food here from you?) a few times, as well as a few offers from company offered programs. I've also looked into travel help at my work (do we have a corporate discount for flights or car rentals?), which our receptionist was happy to give me.
Some thoughts:
Company-offered/paid into programs, like Perkopolis or WorkPerks/Venngo. I've used Perkopolis to look up goods coupons for online shopping, theme park tickets, hotels, car rentals and more. They also have other deals like house cleaning and services, flower delivery, etc.
Cell phone plans. Sometimes work will have connections and can get you a good plan rate to reference.
Flights, hotels and car rentals. My company has a discount on a couple select airlines and as an employee, I can just call, reference our corporate referral code and get a discounts on my personal travel. I know a couple people in our company has also utilized codes like this for personal vacation trips. Your company might have the same, so it can't hurt to ask.
Supplies, like for office and home. A lot of the time companies will have order lines or discount cards that can be used at stores like Staples or for shipping items. We have discount cards for employees to use at Staples, shipping companies (like UPS), as well as at a couple technology sites through our IT department.
Whatever your company sells or supplies (dog food from a pet store, shoes from a footwear brand, groceries from a supermarket, etc). This can also extend into the vendors your company may use, which I've done before too, by just asking if they would extend a deal to you because you work for one of their "partners".
Food. My company once got a message from Swiss chalet that someone responded to, and now we get continuous coupon emails from them, customized "just for us". This is also the best category I've had luck on asking the "proximity" question on.
Shameless Job-title use if you can. If you are police, fire, government or more, you could always ask if there is a discount for you and your line of work. Be proud of what you do :)
Finally... Just Ask!