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	$233.70	9.591%	$256.1142	$256.11	$256.10	$256.10
Purchase #2	$227.28	13.557%	$258.0923	$258.09	$258.10	$258.10
Purchase #3	$94.65	6.625%	$100.9206	$100.92	$100.90	$100.90
Purchase #4	$53.32	11.689%	$59.5526	$59.55	$59.55	$59.60
Purchase #5	$84.64	12.306%	$95.0558	$95.06	$95.05	$95.10
Purchase #6	$225.67	10.593%	$249.5752	$249.58	$249.60	$249.60
Purchase #7	$130.47	8.847%	$142.0127	$142.01	$142.00	$142.00
7 purchase totals =	$1,049.73		$1,161.3234	$1,161.32	$1,161.30	$1,161.40