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	$59.97	3.496%	$62.0666	$62.07	$62.05	$62.10
Purchase #2	$247.56	3.430%	$256.0513	$256.05	$256.05	$256.10
Purchase #3	$72.51	8.450%	$78.6371	$78.64	$78.65	$78.60
Purchase #4	$42.58	6.373%	$45.2936	$45.29	$45.30	$45.30
Purchase #5	$129.97	8.275%	$140.725	$140.73	$140.75	$140.70
Purchase #6	$97.43	7.346%	$104.5872	$104.59	$104.60	$104.60
Purchase #7	$164.30	9.627%	$180.1172	$180.12	$180.10	$180.10
7 purchase totals =	$814.32		$867.4780	$867.49	$867.50	$867.50