Place potato rounds in a large pot of cold water. Bring to a boil and cook until potatoes are tender, about 10 minutes. Drain and let cool for about 5 minutes.
For the dressing, whisk together olive oil, lemon juice, capers, rosemary garlic, salt and pepper in a medium bowl.
Layer one-third of the potatoes and tomatoes in a large serving bowl. Spoon over one-third of the dressing. Repeat two more times with the remaining potatoes, tomatoes and dressing. Cover and let cool in the refrigerator. Serve.