As a retail employee, sorry. Most often, we don't have a choice but to ask. At the company I work for, we have at least 4-5 different collections throughout the year. We're required to ask every single customer, and they track how many donations each register gets. If your number is low, you get questioned as to why. "Are you sure you're asking EVER customer? What are you saying exactly? Try telling them this this and that". I just transferred to a new location and they don't seem as militant, but my last store was just relentless about it. I hate it.
That said, I actually don't mind being asked. I just really dislike doing the asking. It's awkward.