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	$188.71	11.791%	$210.9608	$210.96	$210.95	$211.00
Purchase #2	$17.51	13.743%	$19.9164	$19.92	$19.90	$19.90
Purchase #3	$99.90	3.593%	$103.4894	$103.49	$103.50	$103.50
Purchase #4	$72.34	7.660%	$77.8812	$77.88	$77.90	$77.90
Purchase #5	$58.89	4.426%	$61.4965	$61.50	$61.50	$61.50
Purchase #6	$43.96	5.527%	$46.3897	$46.39	$46.40	$46.40
Purchase #7	$191.26	12.760%	$215.6648	$215.66	$215.65	$215.70
7 purchase totals =	$672.57		$735.7988	$735.80	$735.80	$735.90