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	$196.52	4.812%	$205.9765	$205.98	$206.00	$206.00
Purchase #2	$37.48	7.756%	$40.3869	$40.39	$40.40	$40.40
Purchase #3	$242.27	5.380%	$255.3041	$255.30	$255.30	$255.30
Purchase #4	$202.59	13.616%	$230.1747	$230.17	$230.15	$230.20
Purchase #5	$154.38	11.788%	$172.5783	$172.58	$172.60	$172.60
Purchase #6	$205.29	6.316%	$218.2561	$218.26	$218.25	$218.30
Purchase #7	$26.65	11.718%	$29.7728	$29.77	$29.75	$29.80
7 purchase totals =	$1,065.18		$1,152.4494	$1,152.45	$1,152.45	$1,152.60