Thick skinned asking for discount

Man hands in a script for Predmix. General patient. Whilst I'm dispensing, he asks me "do i get any discount?"

(i'm thinking in my head, wth, why do you think you deserve a discount?) but anyway I responded: "No discount. All our prescription medications are set prices." 

i thought he accepted it and let go of it, but when it came to paying, he asked me again. I said: "We give a 10% seniors discount for ppl with senior citizens' card on over the counter products not on prescription items." He's not old by the way. Full grown man.

He proceeds: "so you don't give any discounts to other ppl when they ask?"

Me rolls my eyes: "We don't just discounts like that for no reason at all."

Him: "Oh ok. the reason i ask is that usually pharmacies give discounts to their regulars customers."

Me knows he is not a regular. He just comes every now and then for antibiotics for his kid. Last time was in April 2012, and the previous time was October 2011. Seriously tell me how regular can you get unless ur child has some chronic medical condition. 

Me: "We don't provide that service here. We have regulars that come in every month with 10 prescriptions each time and we don't give extra discounts on prescription items."

That shut him up. that's true though. $5.80 x 10 medications. that's $58 per month. and pensioners only get $200 per week? (quote me if im wrong) and here you are complaining about paying $20 on an intermittent basis say every 2 months on say a minimum wage (assuming) $400-500 per week. geez... give me a break. You got money to buy toys for your kid, therefore you got money to spend on medications. And stop asking me for discounts out of the blue. Its not like you were purchasing a lot in the store. If you purchase alot of OTC stuff, I MIGHT consider you discounts if I'm in a good mood but otherwise, just don't ask coz (same as what I said last time) - WE ARE NOT THE MARKETS! YOU DONT JUST COME IN AND BARGAIN LIKE YOU DO FOR FRUITS AND VEGETABLES..... ok back to work now.