Here's the C# classes that define the tables which Entity Framework will build
Below these is the SQL code used to create the tables including the relationships with FK contraints

    public class BaseEntity
    {
        public int Id { get; set; }
        public bool Deleted { get; set; }
    }

    public class Store : BaseEntity
    {
        public POSProvider POSProvider { get; set; } // this and POSProviderId link the company that developed the store's POS
        public int POSProviderId { get; set; }
        public string StoreName { get; set; }
        public string Address { get; set; }
        public string ContactPerson { get; set; }
        public string ContactNumber { get; set; }
        public string EmailAddress { get; set; }
        public int Tellers { get; set; }
        public DateTime DateRegistered { get; set; }
    }

    public class Receipt : BaseEntity
    {
        public Store Store { get; set; }
        public int StoreId { get; set; }
        public User User { get; set; }
        public int? UserId { get; set; }
        public string ReceiptNumber { get; set; }
        public decimal ReceiptValue { get; set; }
        public DateTime ReceiptDate { get; set; }
        public decimal Cashback { get; set; }
        public DateTime ValidUntil { get; set; }
        public bool Calculated { get; set; }
        public bool Redeemed { get; set; }
    }

SQL

	CREATE TABLE [dbo].[Stores](
		[Id] [int] IDENTITY(1,1) NOT NULL,
		[POSProviderId] [int] NOT NULL,
		[StoreName] [nvarchar](max) NULL,
		[Address] [nvarchar](max) NULL,
		[ContactPerson] [nvarchar](max) NULL,
		[ContactNumber] [nvarchar](max) NULL,
		[EmailAddress] [nvarchar](max) NULL,
		[Tellers] [int] NOT NULL,
		[DateRegistered] [datetime] NOT NULL,
		[Deleted] [bit] NOT NULL,
	 CONSTRAINT [PK_dbo.Stores] PRIMARY KEY CLUSTERED
	(
		[Id] ASC
	)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
	) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]

	GO

	ALTER TABLE [dbo].[Stores]  WITH CHECK ADD  CONSTRAINT [FK_dbo.Stores_dbo.POSProviders_POSProviderId] FOREIGN KEY([POSProviderId])
	REFERENCES [dbo].[POSProviders] ([Id])
	ON DELETE CASCADE
	GO

	ALTER TABLE [dbo].[Stores] CHECK CONSTRAINT [FK_dbo.Stores_dbo.POSProviders_POSProviderId]
	GO

	CREATE TABLE [dbo].[Receipts](
		[Id] [int] IDENTITY(1,1) NOT NULL,
		[StoreId] [int] NOT NULL,
		[UserId] [int] NULL,
		[ReceiptNumber] [nvarchar](max) NULL,
		[ReceiptValue] [decimal](18, 2) NOT NULL,
		[ReceiptDate] [datetime] NOT NULL,
		[Cashback] [decimal](18, 2) NOT NULL,
		[ValidUntil] [datetime] NOT NULL,
		[Calculated] [bit] NOT NULL,
		[Redeemed] [bit] NOT NULL,
		[Deleted] [bit] NOT NULL,
		[Invoice_Id] [int] NULL,
	 CONSTRAINT [PK_dbo.Receipts] PRIMARY KEY CLUSTERED
	(
		[Id] ASC
	)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
	) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]

	GO

	ALTER TABLE [dbo].[Receipts]  WITH CHECK ADD  CONSTRAINT [FK_dbo.Receipts_dbo.Stores_StoreId] FOREIGN KEY([StoreId])
	REFERENCES [dbo].[Stores] ([Id])
	ON DELETE CASCADE
	GO

	ALTER TABLE [dbo].[Receipts] CHECK CONSTRAINT [FK_dbo.Receipts_dbo.Stores_StoreId]
	GO

	ALTER TABLE [dbo].[Receipts]  WITH CHECK ADD  CONSTRAINT [FK_dbo.Receipts_dbo.Users_UserId] FOREIGN KEY([UserId])
	REFERENCES [dbo].[Users] ([Id])
	GO

	ALTER TABLE [dbo].[Receipts] CHECK CONSTRAINT [FK_dbo.Receipts_dbo.Users_UserId]
	GO