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	$184.57	7.564%	$198.5309	$198.53	$198.55	$198.50
Purchase #2	$164.52	5.697%	$173.8927	$173.89	$173.90	$173.90
Purchase #3	$198.56	12.348%	$223.0782	$223.08	$223.10	$223.10
Purchase #4	$50.72	11.472%	$56.5386	$56.54	$56.55	$56.50
Purchase #5	$7.55	5.279%	$7.9486	$7.95	$7.95	$7.90
Purchase #6	$233.86	9.317%	$255.6487	$255.65	$255.65	$255.60
Purchase #7	$233.94	8.534%	$253.9044	$253.90	$253.90	$253.90
7 purchase totals =	$1,073.72		$1,169.5421	$1,169.54	$1,169.60	$1,169.40