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	$77.76	7.214%	$83.3696	$83.37	$83.35	$83.40
Purchase #2	$114.77	10.866%	$127.2409	$127.24	$127.25	$127.20
Purchase #3	$223.72	4.161%	$233.029	$233.03	$233.05	$233.00
Purchase #4	$177.56	10.526%	$196.25	$196.25	$196.25	$196.30
Purchase #5	$15.26	6.531%	$16.2566	$16.26	$16.25	$16.30
Purchase #6	$150.53	7.842%	$162.3346	$162.33	$162.35	$162.30
Purchase #7	$174.97	10.599%	$193.5151	$193.52	$193.50	$193.50
7 purchase totals =	$934.57		$1,011.9958	$1,012.00	$1,012.00	$1,012.00