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	$52.92	10.235%	$58.3364	$58.34	$58.35	$58.30
Purchase #2	$187.64	3.745%	$194.6671	$194.67	$194.65	$194.70
Purchase #3	$108.31	3.296%	$111.8799	$111.88	$111.90	$111.90
Purchase #4	$133.48	6.865%	$142.6434	$142.64	$142.65	$142.60
Purchase #5	$79.63	8.429%	$86.342	$86.34	$86.35	$86.30
Purchase #6	$87.40	9.288%	$95.5177	$95.52	$95.50	$95.50
Purchase #7	$12.93	3.403%	$13.37	$13.37	$13.35	$13.40
7 purchase totals =	$662.31		$702.7565	$702.76	$702.75	$702.70