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	$130.80	11.721%	$146.1311	$146.13	$146.15	$146.10
Purchase #2	$243.60	5.854%	$257.8603	$257.86	$257.85	$257.90
Purchase #3	$10.50	7.871%	$11.3265	$11.33	$11.35	$11.30
Purchase #4	$167.75	6.647%	$178.9003	$178.90	$178.90	$178.90
Purchase #5	$146.69	13.591%	$166.6266	$166.63	$166.65	$166.60
Purchase #6	$172.26	4.219%	$179.5276	$179.53	$179.55	$179.50
Purchase #7	$204.35	3.225%	$210.9403	$210.94	$210.95	$210.90
7 purchase totals =	$1,075.95		$1,151.3127	$1,151.32	$1,151.40	$1,151.20