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	$185.73	13.135%	$210.1256	$210.13	$210.15	$210.10
Purchase #2	$77.93	3.208%	$80.43	$80.43	$80.45	$80.40
Purchase #3	$40.62	5.356%	$42.7956	$42.80	$42.80	$42.80
Purchase #4	$32.63	5.593%	$34.455	$34.46	$34.45	$34.50
Purchase #5	$53.76	11.125%	$59.7408	$59.74	$59.75	$59.70
Purchase #6	$123.41	3.533%	$127.7701	$127.77	$127.75	$127.80
Purchase #7	$170.87	12.745%	$192.6474	$192.65	$192.65	$192.60
7 purchase totals =	$684.95		$747.9645	$747.98	$748.00	$747.90