I will give once in a great while but I really agree that i dont like it
For a while I would give the extra dollar (or round up to the next dollar, or whatever it was) because it seemed awfully tight fisted to be spending $60 on something but not willing to add $1 to support a good cause. That was before I thought much about whether the "good cause" was actually very good, how much of my dollar went to pay the CEO of the charity and whether the retailer collecting the small change was doing it out of altruism or a desire to get some kind of tax write-off. As I grew to conclude that giving locally makes the most sense I grew more hostile to the "it's only a dollar" brigade.
In the UK it's common to see TV commercials from charities wanting you to call now and set up a payment scheme that's relentlessly focussed on "just two pounds a month, just two pounds a month, just two pounds a month" (two pounds is about $3). The one that annoyed me the most was the Water Aid ad, where in the beginning it showed dark-skinned children in a desaturated but bleak landscape looking hopeless and drinking dirty water from a puddle, and in the end (presumably after receiving my two pounds a month) it showed other dark-skinned children wearing vibrant clothing among grass with everything oversaturated, pumping an abundance of water from a well (so much so they were playing in the water).
Quite aside from wondering how much they spent on the advertising the psychological manipulation put me off supporting them. Presumably the guy who filmed the child drinking dirty water from a puddle didn't care enough to give him a bottle of clean water.