Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$216.77	9.561%	$237.4954	$237.50	$237.50	$237.50
Purchase #2	$225.41	10.314%	$248.6588	$248.66	$248.65	$248.70
Purchase #3	$61.56	3.712%	$63.8451	$63.85	$63.85	$63.80
Purchase #4	$90.98	8.213%	$98.4522	$98.45	$98.45	$98.50
Purchase #5	$230.86	13.750%	$262.6033	$262.60	$262.60	$262.60
Purchase #6	$158.83	3.816%	$164.891	$164.89	$164.90	$164.90
Purchase #7	$34.49	3.439%	$35.6761	$35.68	$35.70	$35.70
7 purchase totals =	$1,018.90		$1,111.6219	$1,111.63	$1,111.65	$1,111.70