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	$102.98	7.850%	$111.0639	$111.06	$111.05	$111.10
Purchase #2	$38.52	8.322%	$41.7256	$41.73	$41.75	$41.70
Purchase #3	$84.26	11.796%	$94.1993	$94.20	$94.20	$94.20
Purchase #4	$38.60	13.660%	$43.8728	$43.87	$43.85	$43.90
Purchase #5	$95.26	7.590%	$102.4902	$102.49	$102.50	$102.50
Purchase #6	$186.38	12.768%	$210.177	$210.18	$210.20	$210.20
Purchase #7	$103.52	7.717%	$111.5086	$111.51	$111.50	$111.50
7 purchase totals =	$649.52		$715.0374	$715.04	$715.05	$715.10