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	$85.82	13.426%	$97.3422	$97.34	$97.35	$97.30
Purchase #2	$39.25	11.137%	$43.6213	$43.62	$43.60	$43.60
Purchase #3	$10.32	8.810%	$11.2292	$11.23	$11.25	$11.20
Purchase #4	$150.88	6.526%	$160.7264	$160.73	$160.75	$160.70
Purchase #5	$58.25	6.305%	$61.9227	$61.92	$61.90	$61.90
Purchase #6	$47.62	12.336%	$53.4944	$53.49	$53.50	$53.50
Purchase #7	$34.82	13.534%	$39.5325	$39.53	$39.55	$39.50
7 purchase totals =	$426.96		$467.8687	$467.86	$467.90	$467.70