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	$199.38	11.485%	$222.2788	$222.28	$222.30	$222.30
Purchase #2	$225.30	8.738%	$244.9867	$244.99	$245.00	$245.00
Purchase #3	$80.29	8.129%	$86.8168	$86.82	$86.80	$86.80
Purchase #4	$138.26	7.405%	$148.4982	$148.50	$148.50	$148.50
Purchase #5	$99.85	11.253%	$111.0861	$111.09	$111.10	$111.10
Purchase #6	$40.69	11.310%	$45.292	$45.29	$45.30	$45.30
Purchase #7	$155.36	3.637%	$161.0104	$161.01	$161.00	$161.00
7 purchase totals =	$939.13		$1,019.9690	$1,019.98	$1,020.00	$1,020.00