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	$190.55	3.262%	$196.7657	$196.77	$196.75	$196.80
Purchase #2	$6.35	8.372%	$6.8816	$6.88	$6.90	$6.90
Purchase #3	$36.85	6.550%	$39.2637	$39.26	$39.25	$39.30
Purchase #4	$22.85	11.659%	$25.5141	$25.51	$25.50	$25.50
Purchase #5	$142.79	10.749%	$158.1385	$158.14	$158.15	$158.10
Purchase #6	$93.42	12.728%	$105.3105	$105.31	$105.30	$105.30
Purchase #7	$132.76	8.488%	$144.0287	$144.03	$144.05	$144.00
7 purchase totals =	$625.57		$675.9028	$675.90	$675.90	$675.90