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	$216.41	7.576%	$232.8052	$232.81	$232.80	$232.80
Purchase #2	$8.31	3.142%	$8.5711	$8.57	$8.55	$8.60
Purchase #3	$200.96	12.855%	$226.7934	$226.79	$226.80	$226.80
Purchase #4	$230.82	11.123%	$256.4941	$256.49	$256.50	$256.50
Purchase #5	$96.26	4.439%	$100.533	$100.53	$100.55	$100.50
Purchase #6	$141.52	10.171%	$155.914	$155.91	$155.90	$155.90
Purchase #7	$79.46	7.511%	$85.4282	$85.43	$85.45	$85.40
7 purchase totals =	$973.74		$1,066.5390	$1,066.53	$1,066.55	$1,066.50