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	$59.46	5.324%	$62.6257	$62.63	$62.65	$62.60
Purchase #2	$166.79	3.394%	$172.4509	$172.45	$172.45	$172.50
Purchase #3	$175.32	9.185%	$191.4231	$191.42	$191.40	$191.40
Purchase #4	$223.37	5.669%	$236.0328	$236.03	$236.05	$236.00
Purchase #5	$12.73	11.260%	$14.1634	$14.16	$14.15	$14.20
Purchase #6	$49.91	11.185%	$55.4924	$55.49	$55.50	$55.50
Purchase #7	$61.87	12.272%	$69.4627	$69.46	$69.45	$69.50
7 purchase totals =	$749.45		$801.6510	$801.64	$801.65	$801.70