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	$90.93	4.520%	$95.04	$95.04	$95.05	$95.00
Purchase #2	$141.25	9.441%	$154.5854	$154.59	$154.60	$154.60
Purchase #3	$147.32	12.531%	$165.7807	$165.78	$165.80	$165.80
Purchase #4	$208.70	3.831%	$216.6953	$216.70	$216.70	$216.70
Purchase #5	$149.87	13.325%	$169.8402	$169.84	$169.85	$169.80
Purchase #6	$91.74	13.163%	$103.8157	$103.82	$103.80	$103.80
Purchase #7	$150.53	11.371%	$167.6468	$167.65	$167.65	$167.60
7 purchase totals =	$980.34		$1,073.4041	$1,073.42	$1,073.45	$1,073.30