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	$196.37	11.769%	$219.4808	$219.48	$219.50	$219.50
Purchase #2	$120.57	6.643%	$128.5795	$128.58	$128.60	$128.60
Purchase #3	$205.76	5.521%	$217.12	$217.12	$217.10	$217.10
Purchase #4	$17.77	9.300%	$19.4226	$19.42	$19.40	$19.40
Purchase #5	$207.80	7.186%	$222.7325	$222.73	$222.75	$222.70
Purchase #6	$127.49	11.732%	$142.4471	$142.45	$142.45	$142.40
Purchase #7	$88.57	10.690%	$98.0381	$98.04	$98.05	$98.00
7 purchase totals =	$964.33		$1,047.8206	$1,047.82	$1,047.85	$1,047.70