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	$224.29	5.500%	$236.626	$236.63	$236.65	$236.60
Purchase #2	$76.48	9.230%	$83.5391	$83.54	$83.55	$83.50
Purchase #3	$43.71	8.516%	$47.4323	$47.43	$47.45	$47.40
Purchase #4	$17.65	5.370%	$18.5978	$18.60	$18.60	$18.60
Purchase #5	$217.41	6.477%	$231.4916	$231.49	$231.50	$231.50
Purchase #6	$56.37	10.166%	$62.1006	$62.10	$62.10	$62.10
Purchase #7	$72.89	13.547%	$82.7644	$82.76	$82.75	$82.80
7 purchase totals =	$708.80		$762.5518	$762.55	$762.60	$762.50