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	$114.65	9.271%	$125.2792	$125.28	$125.30	$125.30
Purchase #2	$227.89	10.393%	$251.5746	$251.57	$251.55	$251.60
Purchase #3	$127.42	5.490%	$134.4154	$134.42	$134.40	$134.40
Purchase #4	$188.47	4.314%	$196.6006	$196.60	$196.60	$196.60
Purchase #5	$194.55	4.224%	$202.7678	$202.77	$202.75	$202.80
Purchase #6	$69.89	5.123%	$73.4705	$73.47	$73.45	$73.50
Purchase #7	$73.28	11.153%	$81.4529	$81.45	$81.45	$81.50
7 purchase totals =	$996.15		$1,065.5610	$1,065.56	$1,065.50	$1,065.70