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	$43.57	4.213%	$45.4056	$45.41	$45.40	$45.40
Purchase #2	$17.57	12.169%	$19.7081	$19.71	$19.70	$19.70
Purchase #3	$104.75	3.393%	$108.3042	$108.30	$108.30	$108.30
Purchase #4	$88.48	12.772%	$99.7807	$99.78	$99.80	$99.80
Purchase #5	$142.32	4.375%	$148.5465	$148.55	$148.55	$148.50
Purchase #6	$49.32	12.403%	$55.4372	$55.44	$55.45	$55.40
Purchase #7	$89.34	9.579%	$97.8979	$97.90	$97.90	$97.90
7 purchase totals =	$535.35		$575.0802	$575.09	$575.10	$575.00