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	$215.72	10.617%	$238.623	$238.62	$238.60	$238.60
Purchase #2	$18.48	6.380%	$19.659	$19.66	$19.65	$19.70
Purchase #3	$28.82	9.555%	$31.5738	$31.57	$31.55	$31.60
Purchase #4	$135.30	7.280%	$145.1498	$145.15	$145.15	$145.10
Purchase #5	$242.75	4.339%	$253.2829	$253.28	$253.30	$253.30
Purchase #6	$212.65	13.557%	$241.479	$241.48	$241.50	$241.50
Purchase #7	$212.78	7.276%	$228.2619	$228.26	$228.25	$228.30
7 purchase totals =	$1,066.50		$1,158.0294	$1,158.02	$1,158.00	$1,158.10