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	$214.89	7.385%	$230.7596	$230.76	$230.75	$230.80
Purchase #2	$20.37	6.564%	$21.7071	$21.71	$21.70	$21.70
Purchase #3	$79.26	3.481%	$82.019	$82.02	$82.00	$82.00
Purchase #4	$144.50	12.332%	$162.3197	$162.32	$162.30	$162.30
Purchase #5	$42.72	9.618%	$46.8288	$46.83	$46.85	$46.80
Purchase #6	$88.96	8.460%	$96.486	$96.49	$96.50	$96.50
Purchase #7	$212.96	5.863%	$225.4458	$225.45	$225.45	$225.40
7 purchase totals =	$803.66		$865.5660	$865.58	$865.55	$865.50