I don’t know why I didn’t mention this sooner. If you want to open toolbar bookmarks in new tabs with Dragon NaturallySpeaking, the Tab Utilities add-on allows you to do that. It’s fairly straightforward. Other nice options include opening direct addresses and history items in new tabs. This works for Vocola “go to <website>” commands as well. You can also see the session history of a tab by clicking it.
Note, though, that links associated with the main page (clicking a recent post link on my blog, for example) will usually open in the same tab depending on the target.