None of the Phaser tilemap demos that
shinkan linked to appear to use floating point scaling or positioning. They look like they effectively have fullscreen mode set to 'Off' (for an in-page embed) and 'pixel rounding' to 'on'. You should get equally seamless results in Construct 2 in those circumstances.
I'm still researching this, but I don't know of any other engines that have solved this when using floating point scaling or positioning. Every other example anyone has pointed to so far simply uses integer scaling and positioning. I'd be interested to find out the technical solutions to this problem.
Note another workaround I mentioned in another thread: using 'low quality' fullscreen mode avoids floating point scaling from letterbox integer scale, and you may be able to then get by only setting 'pixel rounding' on.