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	$87.82	9.267%	$95.9583	$95.96	$95.95	$96.00
Purchase #2	$215.60	12.515%	$242.5823	$242.58	$242.60	$242.60
Purchase #3	$99.43	11.597%	$110.9609	$110.96	$110.95	$111.00
Purchase #4	$175.92	13.585%	$199.8187	$199.82	$199.80	$199.80
Purchase #5	$123.72	6.193%	$131.382	$131.38	$131.40	$131.40
Purchase #6	$47.90	5.403%	$50.488	$50.49	$50.50	$50.50
Purchase #7	$80.82	8.753%	$87.8942	$87.89	$87.90	$87.90
7 purchase totals =	$831.21		$919.0844	$919.08	$919.10	$919.20