If you're like me, that last slip stitch join when you crochet something in the round drives you nuts. I don't want to see where the round begins, especially if it destroys the symmetry of an object.
This is how I do it. Note: For this to work, the rest of your project has to be crocheted with joined rounds. You can do it without joining rounds too, but it sort of defeats the purpose, since then it won't be symmetrical no matter what you do.
Ok, here we go:
Instead of joining the last round with a slip stitch, do as follows: After working the last stitch, cut the yarn. That large loop you see in the image is the last loop on your hook, the one you pull on.
Pull the yarn loop all the way through the stitch.
Find your trusty darning needle. Thread needle with your yarn tail, and poke it through the two loops of the first sc of the round.
Then turn your work so the wrong side faces you. Push needle through the two loops on the back of the last dc of the round.
Now pull yarn through, and this is what it will look like before you adjust the tension to match the rest.
Finished view. Weave in ends, and there you go. Now your flower can look perfectly symmetrical :)
This can be adapted to a number of different stitches. I love using it on hats, among other things.