Give the home node the parent url.

HomeUrlProvider

public class HomeUrlProvider : DefaultUrlProvider
{
    public override string GetUrl(UmbracoContext umbracoContext, int id, Uri current, UrlProviderMode mode)
    {
        var content = umbracoContext.ContentCache.GetById(id);
        if (content.DocumentTypeAlias == "Home" && content.Parent != null)
        {
            return base.GetUrl(umbracoContext, content.Parent.Id, current, mode);
        }

        return base.GetUrl(umbracoContext, id, current, mode);
    }
}

/*    
Register the HomeUrlProvider on ApplicationStarting
*/
UrlProviderResolver.Current.InsertType<HomeUrlProvider>();