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	$213.32	9.285%	$233.1268	$233.13	$233.15	$233.10
Purchase #2	$186.31	10.367%	$205.6248	$205.62	$205.60	$205.60
Purchase #3	$93.89	3.494%	$97.1705	$97.17	$97.15	$97.20
Purchase #4	$220.90	8.825%	$240.3944	$240.39	$240.40	$240.40
Purchase #5	$54.87	10.359%	$60.554	$60.55	$60.55	$60.60
Purchase #6	$18.50	11.569%	$20.6403	$20.64	$20.65	$20.60
Purchase #7	$103.93	7.501%	$111.7258	$111.73	$111.75	$111.70
7 purchase totals =	$891.72		$969.2366	$969.23	$969.25	$969.20