Correct way to handle transaction.cs

using (var conn = new System.Data.SqlClient.SqlConnection(connStr))
{
	if (conn.State != System.Data.ConnectionState.Open) { conn.Open(); }
	var tran = conn.BeginTransaction();

	try
	{
		using (var cmd = conn.CreateCommand())
		{
			cmd.Transaction = tran;
			cmd.CommandText = sql;
			cmd.ExecuteNonQuery();
		}
		// ...

		tran.Commit();
	}
	catch (Exception ex)
	{
		tran.Rollback();
		throw;
	}
	finally
	{
		tran.Dispose();
	}
}