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	$50.95	9.540%	$55.8106	$55.81	$55.80	$55.80
Purchase #2	$65.52	12.567%	$73.7539	$73.75	$73.75	$73.80
Purchase #3	$101.75	9.317%	$111.23	$111.23	$111.25	$111.20
Purchase #4	$96.39	4.793%	$101.01	$101.01	$101.00	$101.00
Purchase #5	$159.90	11.820%	$178.8002	$178.80	$178.80	$178.80
Purchase #6	$233.63	12.120%	$261.946	$261.95	$261.95	$261.90
Purchase #7	$141.72	11.815%	$158.4642	$158.46	$158.45	$158.50
7 purchase totals =	$849.86		$941.0149	$941.01	$941.00	$941.00