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	$194.55	7.143%	$208.4467	$208.45	$208.45	$208.40
Purchase #2	$215.80	4.647%	$225.8282	$225.83	$225.85	$225.80
Purchase #3	$53.63	5.386%	$56.5185	$56.52	$56.50	$56.50
Purchase #4	$246.68	9.413%	$269.9	$269.90	$269.90	$269.90
Purchase #5	$91.83	5.198%	$96.6033	$96.60	$96.60	$96.60
Purchase #6	$89.85	10.468%	$99.2555	$99.26	$99.25	$99.30
Purchase #7	$51.64	6.566%	$55.0307	$55.03	$55.05	$55.00
7 purchase totals =	$943.98		$1,011.5829	$1,011.59	$1,011.60	$1,011.50