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	$49.60	6.520%	$52.8339	$52.83	$52.85	$52.80
Purchase #2	$86.64	6.163%	$91.9796	$91.98	$92.00	$92.00
Purchase #3	$157.45	9.450%	$172.329	$172.33	$172.35	$172.30
Purchase #4	$20.51	4.820%	$21.4986	$21.50	$21.50	$21.50
Purchase #5	$215.55	7.217%	$231.1062	$231.11	$231.10	$231.10
Purchase #6	$117.51	9.326%	$128.469	$128.47	$128.45	$128.50
Purchase #7	$48.60	11.230%	$54.0578	$54.06	$54.05	$54.10
7 purchase totals =	$695.86		$752.2741	$752.28	$752.30	$752.30