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	$213.80	6.670%	$228.0605	$228.06	$228.05	$228.10
Purchase #2	$83.33	7.126%	$89.2681	$89.27	$89.25	$89.30
Purchase #3	$161.81	8.621%	$175.7596	$175.76	$175.75	$175.80
Purchase #4	$93.46	6.420%	$99.4601	$99.46	$99.45	$99.50
Purchase #5	$50.42	4.759%	$52.8195	$52.82	$52.80	$52.80
Purchase #6	$218.69	7.347%	$234.7572	$234.76	$234.75	$234.80
Purchase #7	$129.63	4.561%	$135.5424	$135.54	$135.55	$135.50
7 purchase totals =	$951.14		$1,015.6674	$1,015.67	$1,015.60	$1,015.80