Correct handling DATEs with BIRT can be tricky.
I recommend to always use VARCHAR2 for passing DATE parameters (for report parameters as well as for query parameters). Always verify the data type of your parameters.
In your SQL, always use TO_DATE / TO_CHAR with an explicit date format - otherwise the results would depend on the locale settings.
Next, be sure that the value the user entered is adjusted to a known date-format before it is used in the query. For example, in Germany the SQL date format DD.MM.YYYY HH24:MI:SS is commonly used.
You could create a utility function which adds the missing parts (e.g. the time) automatically. Use an additional argument in this function to specify if it's a "from" date (adds 00:00:00) or a "to" date (adds 23:59:59).
OTOH if the UI forces the user to enter a from-to date without time (say in the format 'MM-DD-YYYY' as in your example), you could just code
WHERE (date >= to_date(?, 'MM-DD-YYYY') and date < to_date(?, 'MM-DD-YYYY') + 1)
Note the usage of < and not <=.
This works because if no time is specified in the format mask, 00:00:00 (in HH24:MI:SS format) is implied.