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	$184.60	6.344%	$196.311	$196.31	$196.30	$196.30
Purchase #2	$10.46	13.399%	$11.8615	$11.86	$11.85	$11.90
Purchase #3	$141.30	9.396%	$154.5765	$154.58	$154.60	$154.60
Purchase #4	$53.54	9.306%	$58.5224	$58.52	$58.50	$58.50
Purchase #5	$113.94	8.329%	$123.4301	$123.43	$123.45	$123.40
Purchase #6	$6.45	8.715%	$7.0121	$7.01	$7.00	$7.00
Purchase #7	$118.25	4.674%	$123.777	$123.78	$123.80	$123.80
7 purchase totals =	$628.54		$675.4906	$675.49	$675.50	$675.50