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	$248.84	5.313%	$262.0609	$262.06	$262.05	$262.10
Purchase #2	$247.94	5.450%	$261.4527	$261.45	$261.45	$261.50
Purchase #3	$52.82	13.370%	$59.882	$59.88	$59.90	$59.90
Purchase #4	$75.53	8.859%	$82.2212	$82.22	$82.20	$82.20
Purchase #5	$43.42	5.445%	$45.7842	$45.78	$45.80	$45.80
Purchase #6	$219.97	9.501%	$240.8693	$240.87	$240.85	$240.90
Purchase #7	$200.98	6.770%	$214.5863	$214.59	$214.60	$214.60
7 purchase totals =	$1,089.50		$1,166.8566	$1,166.85	$1,166.85	$1,167.00