I know there are tax breaks for donating to politrickal parties...people don't usually donate directly to the gov't (that's what taxes are for). Personally I'd rather donate when there's fund-raising for essential services, but seeing as the government funds that by robbing us of our money through taxation, there's not much of a point.
If everyone were to donate money to the US government it would lower the likelihood that the US government would increase taxes, but even then it's no excuse to give money to fund programs one morally objects to