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	$97.51	5.568%	$102.9394	$102.94	$102.95	$102.90
Purchase #2	$92.85	12.548%	$104.5008	$104.50	$104.50	$104.50
Purchase #3	$64.95	11.772%	$72.5959	$72.60	$72.60	$72.60
Purchase #4	$45.54	13.617%	$51.7412	$51.74	$51.75	$51.70
Purchase #5	$58.32	6.142%	$61.902	$61.90	$61.90	$61.90
Purchase #6	$130.47	7.749%	$140.5801	$140.58	$140.60	$140.60
Purchase #7	$243.89	3.640%	$252.7676	$252.77	$252.75	$252.80
7 purchase totals =	$733.53		$787.0270	$787.03	$787.05	$787.00