Utility class for Dapper ORM similar to repository pattern

I have created below repository methods for Dapper ORM.

public SqlMapper.GridReader QueryMultiple(string query, object cmdParams = null, CommandType cmdType = CommandType.Text)
{
     SqlMapper.GridReader objMulti;
     var conn = GetSqlConnection();            
     objMulti = conn.QueryMultiple(query, cmdParams, commandTimeout: 0, commandType: cmdType);                                            
     return objMulti;
}

public IEnumerable<T> GetAll<T>(string query, object cmdParams = null, CommandType cmdType = CommandType.Text) where T : class
{
      IEnumerable<T> objList;
      using (var conn = GetSqlConnection())
      {
           objList = conn.Query<T>(query, param: cmdParams, commandTimeout:0, commandType: cmdType);
           conn.Close();
      }
      return objList;
}

Usage of query method looks fine and connection is closed as soon as the operation completes.

new DapperRepository().Query("zyx").ToList();

But querymultiple returns gridreader. So, does Dapper dispose both connection and reader after read operations are done. Please advise about my approach.

using (SqlMapper.GridReader multiResult = new DapperRepository().QueryMultiple(sql, new { id = id }))
{
   var dbPRTGroup = multiResult.Read<Customer>().Single();
    XXXXX
}