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	$180.45	8.180%	$195.2108	$195.21	$195.20	$195.20
Purchase #2	$52.43	10.256%	$57.8072	$57.81	$57.80	$57.80
Purchase #3	$171.83	5.709%	$181.6398	$181.64	$181.65	$181.60
Purchase #4	$119.71	10.428%	$132.1934	$132.19	$132.20	$132.20
Purchase #5	$104.52	6.561%	$111.3776	$111.38	$111.40	$111.40
Purchase #6	$190.92	7.410%	$205.0672	$205.07	$205.05	$205.10
Purchase #7	$56.36	5.575%	$59.5021	$59.50	$59.50	$59.50
7 purchase totals =	$876.22		$942.7981	$942.80	$942.80	$942.80