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	$153.70	10.132%	$169.2729	$169.27	$169.25	$169.30
Purchase #2	$247.77	11.435%	$276.1025	$276.10	$276.10	$276.10
Purchase #3	$193.95	11.610%	$216.4676	$216.47	$216.45	$216.50
Purchase #4	$41.52	4.102%	$43.2232	$43.22	$43.20	$43.20
Purchase #5	$198.36	10.325%	$218.8407	$218.84	$218.85	$218.80
Purchase #6	$118.46	5.846%	$125.3852	$125.39	$125.40	$125.40
Purchase #7	$49.69	3.811%	$51.5837	$51.58	$51.60	$51.60
7 purchase totals =	$1,003.45		$1,100.8758	$1,100.87	$1,100.85	$1,100.90