It seems lke Berkeley has the highest property taxes in Northern California, so I always allow them a little extra. I usually estimate property taxes at around 1.2% - 1.4%, but this will not take into account any Mello-Roos areas, or any special taxes for emergency services, etc. This will be a very rough estimate
A title company may be able to help you.
In the disclosure report for any property you are interested in will be a section concerning property taxes, which should include a worksheet to estimate what the new taxes will be, once you make a successful bid. Most Realtors supply a disclosure package, before you make your bid.