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	$244.27	7.514%	$262.6244	$262.62	$262.60	$262.60
Purchase #2	$151.79	3.488%	$157.0844	$157.08	$157.10	$157.10
Purchase #3	$117.61	10.628%	$130.1096	$130.11	$130.10	$130.10
Purchase #4	$40.74	4.203%	$42.4523	$42.45	$42.45	$42.50
Purchase #5	$245.51	5.517%	$259.0548	$259.05	$259.05	$259.10
Purchase #6	$41.96	10.579%	$46.3989	$46.40	$46.40	$46.40
Purchase #7	$178.80	5.636%	$188.8772	$188.88	$188.90	$188.90
7 purchase totals =	$1,020.68		$1,086.6016	$1,086.59	$1,086.60	$1,086.70