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	$144.88	12.244%	$162.6191	$162.62	$162.60	$162.60
Purchase #2	$190.54	5.228%	$200.5014	$200.50	$200.50	$200.50
Purchase #3	$27.32	4.417%	$28.5267	$28.53	$28.55	$28.50
Purchase #4	$227.64	8.706%	$247.4583	$247.46	$247.45	$247.50
Purchase #5	$50.68	11.205%	$56.3587	$56.36	$56.35	$56.40
Purchase #6	$51.91	3.254%	$53.5992	$53.60	$53.60	$53.60
Purchase #7	$108.74	10.817%	$120.5024	$120.50	$120.50	$120.50
7 purchase totals =	$801.71		$869.5658	$869.57	$869.55	$869.60