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	$141.50	13.494%	$160.594	$160.59	$160.60	$160.60
Purchase #2	$59.39	12.584%	$66.8636	$66.86	$66.85	$66.90
Purchase #3	$148.71	12.508%	$167.3106	$167.31	$167.30	$167.30
Purchase #4	$147.52	11.694%	$164.771	$164.77	$164.75	$164.80
Purchase #5	$68.74	4.820%	$72.0533	$72.05	$72.05	$72.10
Purchase #6	$155.93	3.163%	$160.8621	$160.86	$160.85	$160.90
Purchase #7	$148.83	7.556%	$160.0756	$160.08	$160.10	$160.10
7 purchase totals =	$870.62		$952.5302	$952.52	$952.50	$952.70