From your Explanation it looks like you need something like below:
1) SELECT Sales , date FROM TABLE_NAME WHERE Sales = ( SELECT MIN(Sales) FROM TABLE_NAME)
2) SELECT Sales , date FROM TABLE_NAME WHERE Sales = ( SELECT MAX(Sales) FROM TABLE_NAME)
In single Query
SELECT Sales , date FROM TABLE_NAME WHERE Sales = ( SELECT MIN(Sales) FROM TABLE_NAME)
UNION
SELECT Sales , date FROM TABLE_NAME WHERE Sales = ( SELECT MAX(Sales) FROM
TABLE_NAME)