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	$158.26	7.138%	$169.5566	$169.56	$169.55	$169.60
Purchase #2	$173.35	5.166%	$182.3053	$182.31	$182.30	$182.30
Purchase #3	$96.60	3.636%	$100.1124	$100.11	$100.10	$100.10
Purchase #4	$145.52	4.857%	$152.5879	$152.59	$152.60	$152.60
Purchase #5	$188.42	8.870%	$205.1329	$205.13	$205.15	$205.10
Purchase #6	$92.41	5.738%	$97.7125	$97.71	$97.70	$97.70
Purchase #7	$104.86	3.665%	$108.7031	$108.70	$108.70	$108.70
7 purchase totals =	$959.42		$1,016.1107	$1,016.11	$1,016.10	$1,016.10