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	$42.28	10.169%	$46.5795	$46.58	$46.60	$46.60
Purchase #2	$140.36	8.253%	$151.9439	$151.94	$151.95	$151.90
Purchase #3	$199.73	11.218%	$222.1357	$222.14	$222.15	$222.10
Purchase #4	$140.43	8.143%	$151.8652	$151.87	$151.85	$151.90
Purchase #5	$77.35	5.703%	$81.7613	$81.76	$81.75	$81.80
Purchase #6	$207.54	3.121%	$214.0173	$214.02	$214.00	$214.00
Purchase #7	$214.47	5.792%	$226.8921	$226.89	$226.90	$226.90
7 purchase totals =	$1,022.16		$1,095.1950	$1,095.20	$1,095.20	$1,095.20