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	$212.99	6.760%	$227.3881	$227.39	$227.40	$227.40
Purchase #2	$90.91	4.106%	$94.6428	$94.64	$94.65	$94.60
Purchase #3	$215.94	3.670%	$223.865	$223.87	$223.85	$223.90
Purchase #4	$115.74	13.492%	$131.3556	$131.36	$131.35	$131.40
Purchase #5	$240.89	6.439%	$256.4009	$256.40	$256.40	$256.40
Purchase #6	$247.83	5.486%	$261.426	$261.43	$261.45	$261.40
Purchase #7	$161.84	6.429%	$172.2447	$172.24	$172.25	$172.20
7 purchase totals =	$1,286.14		$1,367.3231	$1,367.33	$1,367.35	$1,367.30