making a square gimp brush with rounded corners?

i’m trying to edit a square brush in gimp and giving its corners more roundness.

heres what the brush looks like now

http://puu.sh/1GMzX

as you can see the edges are a bit pointy. is there a way i can edit it to have the corners more round-ish?

Select the Rectangle Select Tool :
http://i.imgur.com/7xpYt.jpg

On your image, make the selection you want , adjust position and size if needed

Enable “Rounded Corner” in the “Rectangle Select” settings
http://i.imgur.com/T7JwW.jpg

Edit the Radius setting to round it the way you need
http://i.imgur.com/eVQhZ.jpg

Select the Bucket Fill Tool :
http://i.imgur.com/gclRh.jpg

And fill the selection with the color you want.

(this is for GIMP 2.6.x but it works exactly the same in 2.8.x)

thanks for the help, but is there a way i can turn that rounded rectangle into just a brush and not a selection tool?

edit: nevermind. i found a good tutorial on how to make an image a brush. http://brainsongimp.blogspot.com/2007/08/making-brushes.html