BER is caused by a maldistribution of calcium in the fruit... not enough calcium gets to the end so it rots. It's often the result of uneven watering, but sometimes it is just unavoidable. Some say to supplement the plants with something containing calcium but if the calcium isn't getting to the end of the fruit it doesn't necessarily mean there's a deficiency. Watering evenly is a start...
Roma and other paste-type tomatoes are the most vulnerable, while cherries are probably the least. Make sure watering is even (don't let them wilt and then over-water for example) and usually they will just outgrow it. My Opalkas (the only paste type I grow) will get a few fruits with BER earlier in the producing season but then it fades off. I mulch my tomatoes and rarely if ever water. I have not watered at all this year, and even in this drought, my tomatoes are pumping out lush leaves and fruit. BER has never been too big a problem for me - stink bugs, hornworms, fruit worms, etc are worse.