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	$88.25	7.281%	$94.6755	$94.68	$94.70	$94.70
Purchase #2	$13.82	4.406%	$14.4289	$14.43	$14.45	$14.40
Purchase #3	$90.50	6.117%	$96.0359	$96.04	$96.05	$96.00
Purchase #4	$15.45	11.533%	$17.2318	$17.23	$17.25	$17.20
Purchase #5	$115.49	10.393%	$127.4929	$127.49	$127.50	$127.50
Purchase #6	$172.42	3.711%	$178.8185	$178.82	$178.80	$178.80
Purchase #7	$169.98	9.344%	$185.8629	$185.86	$185.85	$185.90
7 purchase totals =	$665.91		$714.5464	$714.55	$714.60	$714.50