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	$157.88	10.197%	$173.979	$173.98	$174.00	$174.00
Purchase #2	$57.98	7.491%	$62.3233	$62.32	$62.30	$62.30
Purchase #3	$95.46	7.720%	$102.8295	$102.83	$102.85	$102.80
Purchase #4	$105.32	7.131%	$112.8304	$112.83	$112.85	$112.80
Purchase #5	$42.67	4.244%	$44.4809	$44.48	$44.50	$44.50
Purchase #6	$222.89	5.823%	$235.8689	$235.87	$235.85	$235.90
Purchase #7	$150.47	9.120%	$164.1929	$164.19	$164.20	$164.20
7 purchase totals =	$832.67		$896.5049	$896.50	$896.55	$896.50