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	$118.63	10.120%	$130.6354	$130.64	$130.65	$130.60
Purchase #2	$97.45	4.727%	$102.0565	$102.06	$102.05	$102.10
Purchase #3	$152.54	8.551%	$165.5837	$165.58	$165.60	$165.60
Purchase #4	$173.86	3.149%	$179.3349	$179.33	$179.35	$179.30
Purchase #5	$146.78	4.288%	$153.0739	$153.07	$153.05	$153.10
Purchase #6	$229.81	7.681%	$247.4617	$247.46	$247.45	$247.50
Purchase #7	$208.83	4.668%	$218.5782	$218.58	$218.60	$218.60
7 purchase totals =	$1,127.90		$1,196.7243	$1,196.72	$1,196.75	$1,196.80