In order to push images to a local registry rather than the main Docker Hub, images need to be tagged with the local registry address.
Also, it would be useful to be able to tag a built image as 'latest' following a successful build, without having to resort to e.g. a shell script to perform this.
It appears that docker-java does have 'tag' implemented, so to add the ability to do this to the docker-build-step-plugin should be trivial (I hope!). Unfortunately I'm not familiar with coding for Jenkins, so don't feel confident implementing it myself.