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	$44.60	4.601%	$46.652	$46.65	$46.65	$46.70
Purchase #2	$195.74	9.342%	$214.026	$214.03	$214.05	$214.00
Purchase #3	$67.89	8.311%	$73.5323	$73.53	$73.55	$73.50
Purchase #4	$72.32	10.755%	$80.098	$80.10	$80.10	$80.10
Purchase #5	$158.65	13.125%	$179.4728	$179.47	$179.45	$179.50
Purchase #6	$84.76	5.262%	$89.2201	$89.22	$89.20	$89.20
Purchase #7	$76.59	9.220%	$83.6516	$83.65	$83.65	$83.70
7 purchase totals =	$700.55		$766.6528	$766.65	$766.65	$766.70