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	$191.46	7.378%	$205.5859	$205.59	$205.60	$205.60
Purchase #2	$6.93	10.288%	$7.643	$7.64	$7.65	$7.60
Purchase #3	$50.51	3.544%	$52.3001	$52.30	$52.30	$52.30
Purchase #4	$157.37	13.257%	$178.2325	$178.23	$178.25	$178.20
Purchase #5	$52.60	13.721%	$59.8172	$59.82	$59.80	$59.80
Purchase #6	$214.32	7.694%	$230.8098	$230.81	$230.80	$230.80
Purchase #7	$194.38	12.774%	$219.2101	$219.21	$219.20	$219.20
7 purchase totals =	$867.57		$953.5986	$953.60	$953.60	$953.50