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	$119.58	9.242%	$130.6316	$130.63	$130.65	$130.60
Purchase #2	$82.85	8.177%	$89.6246	$89.62	$89.60	$89.60
Purchase #3	$6.38	12.784%	$7.1956	$7.20	$7.20	$7.20
Purchase #4	$68.52	3.463%	$70.8928	$70.89	$70.90	$70.90
Purchase #5	$125.46	13.837%	$142.8199	$142.82	$142.80	$142.80
Purchase #6	$177.83	9.603%	$194.907	$194.91	$194.90	$194.90
Purchase #7	$87.70	4.235%	$91.4141	$91.41	$91.40	$91.40
7 purchase totals =	$668.32		$727.4856	$727.48	$727.45	$727.40