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	$168.58	10.200%	$185.7752	$185.78	$185.80	$185.80
Purchase #2	$181.41	10.679%	$200.7828	$200.78	$200.80	$200.80
Purchase #3	$182.57	9.455%	$199.832	$199.83	$199.85	$199.80
Purchase #4	$51.99	8.437%	$56.3764	$56.38	$56.40	$56.40
Purchase #5	$183.51	4.846%	$192.4029	$192.40	$192.40	$192.40
Purchase #6	$161.28	5.549%	$170.2294	$170.23	$170.25	$170.20
Purchase #7	$10.92	4.616%	$11.4241	$11.42	$11.40	$11.40
7 purchase totals =	$940.26		$1,016.8228	$1,016.82	$1,016.90	$1,016.80