wp have all versions like 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, etc (and 1.2.x minor updates)
I think it is good idea to use similar versioning.
If next release after 1.1 is big update, it is not necesarry to bump version to 1.5...
If next release after 1.8 is big...