Inserting registry and retrieving ID generated by SQL Server 2012

I want to insert a record into a table, retrieve the ID that was generated by AUTO_INCREMENT and insert records into other tables, using that ID. But, I want to do this all using BeginTransaction .

How could I do this?

I'm doing it this way:

    public void venda(Venda_ResumidaModel objVenda)
    {
        using (SqlConnection connection = new SqlConnection("SERVER= ;" + "DATABASE= ;" + "UID= ;" + "PASSWORD=;"))
        {
            SqlCommand cmd = connection.CreateCommand();
            SqlTransaction transaction = null;

            try
            {
                // BeginTransaction() Requires Open Connection
                connection.Open();

                transaction = connection.BeginTransaction();

                // Assign Transaction to Command
                cmd.Transaction = transaction;

                // Execute 1st Command
                cmd.CommandText = "INSERT INTO Venda(ID_Pessoa, ID_Caixa, ID_PDV, ID_Deposito, Data, Itens, Valor, Desconto, Valor_Final, Cancelada, Valor_Dinheiro, Valor_Cheque, Valor_Cartao, Valor_Crediario, Valor_Troco) " +
                "values (@ID_Pessoa, @ID_Caixa, @ID_PDV, @ID_Deposito, getdate(), @Itens, @Valor, @Desconto, @Valor_Final, @Cancelada, @Valor_Dinheiro, @Valor_Cheque, @Valor_Cartao, @Valor_Crediario, @Valor_Troco)";


            cmd.Parameters.AddWithValue("@ID_Pessoa", objVenda.ObjProprietario.ID_Pessoa);
            cmd.Parameters.AddWithValue("@ID_Caixa", objVenda.ObjCaixa.ID_Caixa);
            cmd.Parameters.AddWithValue("@ID_PDV", 1);
            cmd.Parameters.AddWithValue("@ID_Deposito", 1);
            cmd.Parameters.AddWithValue("@Itens", objVenda.Itens);
            cmd.Parameters.AddWithValue("@Valor", objVenda.Valor_Venda);
            cmd.Parameters.AddWithValue("@Desconto", objVenda.Desconto);
            cmd.Parameters.AddWithValue("@Valor_Final", objVenda.Valor_final);
            cmd.Parameters.AddWithValue("@Cancelada", 'N');
            cmd.Parameters.AddWithValue("@Valor_Dinheiro", objVenda.Valor_dinheiro);
            cmd.Parameters.AddWithValue("@Valor_Cheque", objVenda.Valor_cheque);
            cmd.Parameters.AddWithValue("@Valor_Cartao", objVenda.Valor_cartao);
            cmd.Parameters.AddWithValue("@Valor_Crediario", objVenda.Valor_crediario);
            cmd.Parameters.AddWithValue("@Valor_Troco", objVenda.Valor_troco);

            cmd.Parameters.AddWithValue("@id", 0).Direction = ParameterDirection.Output;

            cmd.ExecuteScalar();


                // Execute 2nd Command
            if (objVenda.Valor_dinheiro > 0)
            {
                cmd.CommandText = "Insert into Caixa_Movimentacao (Caixa, Data_Movimentacao, Tipo, Valor, Forma_Pagamento)" +
                    "values (@Caixa, getdate(), 6, @Valor_, 1)";


                cmd.Parameters.AddWithValue("@Caixa", objVenda.ObjCaixa.ID_Caixa);
                cmd.Parameters.AddWithValue("@Valor_", objVenda.ValorVenda);

                cmd.ExecuteNonQuery();
            }





            int retorno = Convert.ToInt32(cmd.Parameters["@id"].Value);

            cmd.CommandText = "insert into Venda_Item_Servico (Id_venda, ID_Servico, Valor_Venda, Desconto, Valor_Total) values ("+ retorno +", @ID_Servico, @Valor_Venda, @Desconto, @Valor_Total)";
            //cmd.Parameters.AddWithValue("@id", objVenda);
            cmd.Parameters.AddWithValue("@ID_Servico", objVenda.ObjServico.Codigo);
            cmd.Parameters.AddWithValue("@Valor_Venda", objVenda.ObjServico.Valor_Venda);
            //cmd.Parameters.AddWithValue("@Desconto", objVenda);
            cmd.Parameters.AddWithValue("@Valor_Total", objVenda.ObjServico.Valor_Venda);

            cmd.ExecuteNonQuery();

            transaction.Commit();

            }
            catch
            {
                transaction.Rollback();
                throw;
            }
            finally
            {
                connection.Close();
            }
        }