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	$87.32	13.864%	$99.426	$99.43	$99.45	$99.40
Purchase #2	$29.56	7.187%	$31.6845	$31.68	$31.70	$31.70
Purchase #3	$191.62	13.862%	$218.1824	$218.18	$218.20	$218.20
Purchase #4	$143.33	10.328%	$158.1331	$158.13	$158.15	$158.10
Purchase #5	$97.74	5.567%	$103.1812	$103.18	$103.20	$103.20
Purchase #6	$91.96	13.648%	$104.5107	$104.51	$104.50	$104.50
Purchase #7	$213.61	4.664%	$223.5728	$223.57	$223.55	$223.60
7 purchase totals =	$855.14		$938.6907	$938.68	$938.75	$938.70