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	$87.73	8.860%	$95.5029	$95.50	$95.50	$95.50
Purchase #2	$163.28	9.566%	$178.8994	$178.90	$178.90	$178.90
Purchase #3	$168.76	3.664%	$174.9434	$174.94	$174.95	$174.90
Purchase #4	$173.29	10.514%	$191.5097	$191.51	$191.50	$191.50
Purchase #5	$198.63	13.543%	$225.5305	$225.53	$225.55	$225.50
Purchase #6	$84.77	6.226%	$90.0478	$90.05	$90.05	$90.00
Purchase #7	$6.26	5.483%	$6.6032	$6.60	$6.60	$6.60
7 purchase totals =	$882.72		$963.0369	$963.03	$963.05	$962.90