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	$64.56	4.224%	$67.287	$67.29	$67.30	$67.30
Purchase #2	$16.60	4.281%	$17.3106	$17.31	$17.30	$17.30
Purchase #3	$25.49	8.106%	$27.5562	$27.56	$27.55	$27.60
Purchase #4	$47.33	10.794%	$52.4388	$52.44	$52.45	$52.40
Purchase #5	$80.90	10.395%	$89.3096	$89.31	$89.30	$89.30
Purchase #6	$97.97	8.140%	$105.9448	$105.94	$105.95	$105.90
Purchase #7	$44.28	3.567%	$45.8595	$45.86	$45.85	$45.90
7 purchase totals =	$377.13		$405.7065	$405.71	$405.70	$405.70