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	$210.61	3.654%	$218.3057	$218.31	$218.30	$218.30
Purchase #2	$233.43	7.792%	$251.6189	$251.62	$251.60	$251.60
Purchase #3	$214.80	3.580%	$222.4898	$222.49	$222.50	$222.50
Purchase #4	$8.50	11.807%	$9.5036	$9.50	$9.50	$9.50
Purchase #5	$65.51	7.325%	$70.3086	$70.31	$70.30	$70.30
Purchase #6	$179.77	5.420%	$189.5135	$189.51	$189.50	$189.50
Purchase #7	$59.32	4.169%	$61.7931	$61.79	$61.80	$61.80
7 purchase totals =	$971.94		$1,023.5332	$1,023.53	$1,023.50	$1,023.50