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	$241.50	5.430%	$254.6135	$254.61	$254.60	$254.60
Purchase #2	$41.75	9.743%	$45.8177	$45.82	$45.80	$45.80
Purchase #3	$90.58	4.871%	$94.9922	$94.99	$95.00	$95.00
Purchase #4	$217.90	3.206%	$224.8859	$224.89	$224.90	$224.90
Purchase #5	$152.26	13.263%	$172.4542	$172.45	$172.45	$172.50
Purchase #6	$173.75	13.287%	$196.8362	$196.84	$196.85	$196.80
Purchase #7	$55.63	7.236%	$59.6554	$59.66	$59.65	$59.70
7 purchase totals =	$973.37		$1,049.2551	$1,049.26	$1,049.25	$1,049.30