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	$65.85	3.377%	$68.0738	$68.07	$68.05	$68.10
Purchase #2	$56.83	6.781%	$60.6836	$60.68	$60.70	$60.70
Purchase #3	$229.82	6.254%	$244.1929	$244.19	$244.20	$244.20
Purchase #4	$200.65	13.173%	$227.0816	$227.08	$227.10	$227.10
Purchase #5	$99.54	12.368%	$111.8511	$111.85	$111.85	$111.90
Purchase #6	$141.26	7.505%	$151.8616	$151.86	$151.85	$151.90
Purchase #7	$144.80	5.535%	$152.8147	$152.81	$152.80	$152.80
7 purchase totals =	$938.75		$1,016.5593	$1,016.54	$1,016.55	$1,016.70