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	$85.33	13.338%	$96.7113	$96.71	$96.70	$96.70
Purchase #2	$105.64	8.671%	$114.8	$114.80	$114.80	$114.80
Purchase #3	$177.28	12.333%	$199.1439	$199.14	$199.15	$199.10
Purchase #4	$171.92	10.795%	$190.4788	$190.48	$190.50	$190.50
Purchase #5	$147.58	5.317%	$155.4268	$155.43	$155.45	$155.40
Purchase #6	$85.33	12.673%	$96.1439	$96.14	$96.15	$96.10
Purchase #7	$174.31	3.504%	$180.4178	$180.42	$180.40	$180.40
7 purchase totals =	$947.39		$1,033.1225	$1,033.12	$1,033.15	$1,033.00