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	$106.64	5.563%	$112.5724	$112.57	$112.55	$112.60
Purchase #2	$216.39	4.789%	$226.7529	$226.75	$226.75	$226.80
Purchase #3	$53.77	10.419%	$59.3723	$59.37	$59.35	$59.40
Purchase #4	$199.41	4.730%	$208.8421	$208.84	$208.85	$208.80
Purchase #5	$190.26	3.321%	$196.5785	$196.58	$196.60	$196.60
Purchase #6	$248.29	10.772%	$275.0358	$275.04	$275.05	$275.00
Purchase #7	$117.72	5.120%	$123.7473	$123.75	$123.75	$123.70
7 purchase totals =	$1,132.48		$1,202.9013	$1,202.90	$1,202.90	$1,202.90