Sass Background Image mixin

I'm kind of new to Sass, but I'm attempting to create a workflow for myself. I generate "color packs" for my theme designs and need to specify the following variables for my mixin. Is there a better way to do this?:

// folder,filename,extension,repeat,x-pos,y-pos
@mixin background ($folder:style1, $img:file, $type:png, $repeat:no-repeat, $x:0, $y:0) {
    background-image: url(./images/#{$folder}/#{$img}.#{$type});
    background-repeat: #{$repeat};
    background-position: #{$x}px #{$y}px;
}

I'm inserting like so:

#nav {
  @include background(style2,myimage,png,repeat-x,10,10);
}

which yields this:

#nav {
  background-image: url(./images/style2/myimage.png);
  background-repeat: repeat-x;
  background-position: 10px 10px;
}

I'd prefer to use CSS shorthand when possible, but I ran into errors with the output. I'd appreciate any expert advice if this is not the best way to do it.