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	$56.89	8.550%	$61.7541	$61.75	$61.75	$61.80
Purchase #2	$233.96	7.379%	$251.2239	$251.22	$251.20	$251.20
Purchase #3	$89.58	11.209%	$99.621	$99.62	$99.60	$99.60
Purchase #4	$169.67	5.165%	$178.4335	$178.43	$178.45	$178.40
Purchase #5	$150.58	7.863%	$162.4201	$162.42	$162.40	$162.40
Purchase #6	$86.25	6.469%	$91.8295	$91.83	$91.85	$91.80
Purchase #7	$192.50	13.376%	$218.2488	$218.25	$218.25	$218.20
7 purchase totals =	$979.43		$1,063.5309	$1,063.52	$1,063.50	$1,063.40