You have to sync your tabs and bookmarks together because we don't have an option to sync only the bookmarks. On your Mac, open System Preferences > iCloud and mark Safari, and on your iPhone and iPad, open Settings > iCloud and turn on Safari
I posted too soon! Just found a way to accomplish what I want. If you want to do the same, do not sync Safari via iCloud. Instead, when you sync your device to iTunes on your Mac, you will see a Sync Safari Bookmarks tickbox under the Info tab. This syncs bookmarks but not tabs.