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	$219.66	9.757%	$241.0922	$241.09	$241.10	$241.10
Purchase #2	$69.62	4.609%	$72.8288	$72.83	$72.85	$72.80
Purchase #3	$103.93	13.808%	$118.2807	$118.28	$118.30	$118.30
Purchase #4	$243.26	13.484%	$276.0612	$276.06	$276.05	$276.10
Purchase #5	$246.64	11.464%	$274.9148	$274.91	$274.90	$274.90
Purchase #6	$137.74	5.290%	$145.0264	$145.03	$145.05	$145.00
Purchase #7	$79.61	11.320%	$88.6219	$88.62	$88.60	$88.60
7 purchase totals =	$1,100.46		$1,216.8260	$1,216.82	$1,216.85	$1,216.80