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	$187.63	9.368%	$205.2072	$205.21	$205.20	$205.20
Purchase #2	$46.35	13.568%	$52.6388	$52.64	$52.65	$52.60
Purchase #3	$127.86	11.646%	$142.7506	$142.75	$142.75	$142.80
Purchase #4	$82.95	10.314%	$91.5055	$91.51	$91.50	$91.50
Purchase #5	$192.29	9.452%	$210.4653	$210.47	$210.45	$210.50
Purchase #6	$189.71	5.650%	$200.4286	$200.43	$200.45	$200.40
Purchase #7	$107.93	5.689%	$114.0701	$114.07	$114.05	$114.10
7 purchase totals =	$934.72		$1,017.0661	$1,017.08	$1,017.05	$1,017.10