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	$191.87	10.762%	$212.519	$212.52	$212.50	$212.50
Purchase #2	$53.98	12.127%	$60.5262	$60.53	$60.55	$60.50
Purchase #3	$96.61	7.704%	$104.0528	$104.05	$104.05	$104.10
Purchase #4	$100.96	8.542%	$109.584	$109.58	$109.60	$109.60
Purchase #5	$88.37	7.781%	$95.2461	$95.25	$95.25	$95.20
Purchase #6	$134.54	7.447%	$144.5592	$144.56	$144.55	$144.60
Purchase #7	$127.97	11.777%	$143.041	$143.04	$143.05	$143.00
7 purchase totals =	$794.30		$869.5283	$869.53	$869.55	$869.50