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	$241.29	5.285%	$254.0422	$254.04	$254.05	$254.00
Purchase #2	$238.79	6.184%	$253.5568	$253.56	$253.55	$253.60
Purchase #3	$179.35	9.414%	$196.234	$196.23	$196.25	$196.20
Purchase #4	$149.66	10.494%	$165.3653	$165.37	$165.35	$165.40
Purchase #5	$144.37	6.245%	$153.3859	$153.39	$153.40	$153.40
Purchase #6	$61.25	3.593%	$63.4507	$63.45	$63.45	$63.50
Purchase #7	$11.91	5.390%	$12.5519	$12.55	$12.55	$12.60
7 purchase totals =	$1,026.62		$1,098.5868	$1,098.59	$1,098.60	$1,098.70