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	$199.56	5.720%	$210.9748	$210.97	$210.95	$211.00
Purchase #2	$225.77	5.640%	$238.5034	$238.50	$238.50	$238.50
Purchase #3	$74.98	3.593%	$77.674	$77.67	$77.65	$77.70
Purchase #4	$179.46	11.162%	$199.4913	$199.49	$199.50	$199.50
Purchase #5	$45.83	11.170%	$50.9492	$50.95	$50.95	$50.90
Purchase #6	$142.57	7.238%	$152.8892	$152.89	$152.90	$152.90
Purchase #7	$77.40	7.816%	$83.4496	$83.45	$83.45	$83.40
7 purchase totals =	$945.57		$1,013.9315	$1,013.92	$1,013.90	$1,013.90