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	$201.32	3.106%	$207.573	$207.57	$207.55	$207.60
Purchase #2	$92.59	13.637%	$105.2165	$105.22	$105.20	$105.20
Purchase #3	$103.29	9.269%	$112.864	$112.86	$112.85	$112.90
Purchase #4	$74.54	10.715%	$82.527	$82.53	$82.55	$82.50
Purchase #5	$203.83	13.223%	$230.7824	$230.78	$230.80	$230.80
Purchase #6	$210.46	7.286%	$225.7941	$225.79	$225.80	$225.80
Purchase #7	$73.95	11.390%	$82.3729	$82.37	$82.35	$82.40
7 purchase totals =	$959.98		$1,047.1299	$1,047.12	$1,047.10	$1,047.20