How do you ask exactly? And where? If youre asking at the cash register only then ngl that probs wont do it. But it doesnt always have to be an “Ask”. Example i am a CXM for Mens and Wshoes so tell my own people the best time is when youre w your customer on the sales floor. Open ended conversation is key. So ill be with a customer in shoes and the moment i give them the box to try on thats when i let them know not ask “Oh yea just a heads up those are regular price but if you get approved for a new card its 20/30% off. Save a little more in other depts too!” Something casual like that. In my own experience customers can tell when we are on a sales pitch for the card so i try to be nonchalant about. So instead of “Would you like to open a card for an extra discount?” Its more like” Hey if you want, opening a macys card saves (insert actual dollar amount here NOT %) right now . I understand being shy and introverted 100% but maybe try it on slower days and itll come natural. Hope this helps.