5 requests already - wow, that's quite a lot if your child has only just started. Are they official charities that the school helps or just parents who've set up an aid thing for something going on in their home countries?
Our old school here used to help a Cambodian charity and a couple of local ones and I was happy to give and when the Chilean earthquake happened, some parents from Chile set up a fund and that was well supported, but it was never anything too excessive or frequent.
The school we're in now help a charity in Vietnam which is a good charity and I'm happy to help there most of the time but it depends on what kind fund raising they're doing at a particular time.
One of the schools did an art auction and they had reserve prices which I thought were a little on the high side so I didn't bother going, but it went quite well and the rich parents all went and forked out megabucks for a couple of stick figure pictures

But if they can afford to do that, then that's great, however I don't think school were ticking off names to see who were the supporters and who weren't.
There was also a t-shirt thing at one of our old schools once and our kids didn't want one so we didn't get them - the school were a bit sneaky over that one though I thought and announced that Friday was charity t-shirt wearing day and if you had the charity t-shirt you could wear it all day. Perhaps they were hoping that people would buy them so their kids wouldn't be the odd ones out, but ours still didn't want one and there were quite a few who just wore the normal school top that day, so if that was their plan, it didn't work too well

But don't ever feel forced to give just because everyone else is. Whenever we have sponsored swims and things, I just put mine and my husbands names down on the form and perhaps a grandparent or two, sponsor a small amount per lap and then I pay it all myself - we can't be bothered going around knocking on strangers doors for sponsorship so we just keep it in the family.