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	$97.47	6.344%	$103.6535	$103.65	$103.65	$103.70
Purchase #2	$163.57	10.705%	$181.0802	$181.08	$181.10	$181.10
Purchase #3	$234.60	9.524%	$256.9433	$256.94	$256.95	$256.90
Purchase #4	$122.77	3.681%	$127.2892	$127.29	$127.30	$127.30
Purchase #5	$101.66	8.712%	$110.5166	$110.52	$110.50	$110.50
Purchase #6	$190.29	5.309%	$200.3925	$200.39	$200.40	$200.40
Purchase #7	$77.32	13.231%	$87.5502	$87.55	$87.55	$87.60
7 purchase totals =	$987.68		$1,067.4255	$1,067.42	$1,067.45	$1,067.50