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	$13.32	5.734%	$14.0838	$14.08	$14.10	$14.10
Purchase #2	$86.30	6.227%	$91.6739	$91.67	$91.65	$91.70
Purchase #3	$195.31	7.326%	$209.6184	$209.62	$209.60	$209.60
Purchase #4	$46.78	3.398%	$48.3696	$48.37	$48.35	$48.40
Purchase #5	$141.77	10.309%	$156.3851	$156.39	$156.40	$156.40
Purchase #6	$72.50	7.260%	$77.7635	$77.76	$77.75	$77.80
Purchase #7	$89.32	13.654%	$101.5158	$101.52	$101.50	$101.50
7 purchase totals =	$645.30		$699.4101	$699.41	$699.35	$699.50