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	$49.76	7.634%	$53.5587	$53.56	$53.55	$53.60
Purchase #2	$222.33	13.188%	$251.6509	$251.65	$251.65	$251.70
Purchase #3	$58.46	5.561%	$61.711	$61.71	$61.70	$61.70
Purchase #4	$234.45	11.631%	$261.7189	$261.72	$261.70	$261.70
Purchase #5	$131.36	10.726%	$145.4497	$145.45	$145.45	$145.40
Purchase #6	$59.69	4.470%	$62.3581	$62.36	$62.35	$62.40
Purchase #7	$205.32	12.422%	$230.8249	$230.82	$230.80	$230.80
7 purchase totals =	$961.37		$1,067.2722	$1,067.27	$1,067.20	$1,067.30