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	$23.69	8.753%	$25.7636	$25.76	$25.75	$25.80
Purchase #2	$181.56	7.311%	$194.8339	$194.83	$194.85	$194.80
Purchase #3	$115.45	10.411%	$127.4695	$127.47	$127.45	$127.50
Purchase #4	$205.96	6.572%	$219.4957	$219.50	$219.50	$219.50
Purchase #5	$210.52	5.654%	$222.4228	$222.42	$222.40	$222.40
Purchase #6	$238.59	7.828%	$257.2668	$257.27	$257.25	$257.30
Purchase #7	$103.46	11.800%	$115.6683	$115.67	$115.65	$115.70
7 purchase totals =	$1,079.23		$1,162.9206	$1,162.92	$1,162.85	$1,163.00