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	$193.58	13.560%	$219.8294	$219.83	$219.85	$219.80
Purchase #2	$48.56	6.167%	$51.5547	$51.55	$51.55	$51.60
Purchase #3	$60.36	8.682%	$65.6005	$65.60	$65.60	$65.60
Purchase #4	$121.81	4.321%	$127.0734	$127.07	$127.05	$127.10
Purchase #5	$81.29	5.383%	$85.6658	$85.67	$85.65	$85.70
Purchase #6	$234.46	4.376%	$244.72	$244.72	$244.70	$244.70
Purchase #7	$59.80	3.434%	$61.8535	$61.85	$61.85	$61.90
7 purchase totals =	$799.86		$856.2973	$856.29	$856.25	$856.40