IsEditingCommerceRole.cs

public class IsEditingCommerceRole : VirtualRoleProviderBase
	{
		public const string Name = "IsEditingCommerceRole";

		private readonly IContentRepository _contentRepository;

		public IsEditingCommerceRole()
		{
			this._contentRepository = ServiceLocator.Current.GetInstance<IContentRepository>();
		}

		public override bool IsInVirtualRole(IPrincipal principal, object context)
		{
			IContent startPage = this._contentRepository.Get<IContent>(ContentReference.StartPage);

			//Replace logic with your logic on how to determine what site editor visits.
			return startPage is CommerceSiteStartPage;
		}
	}