+++ I searched for the Issue but found nothing +++
If I want to Teleport to the Coordinates 0 5 0 (/tp 0 5 0), I get teleported to 0.5 5 0.5. But I want to Teleport me to 0 5 0 not these. To teleport to 0 5 0 I need to write /tp 0.0001 5 0.0001. Is this maybe a bug?
Not a bug. Decimal defaults to 0.5 (to place player in middle of block as is most commonly used) and adding your own overwrites it. You can use a simple 0.0 instead of 0.0001.