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	$48.58	7.768%	$52.3537	$52.35	$52.35	$52.40
Purchase #2	$82.93	5.451%	$87.4505	$87.45	$87.45	$87.50
Purchase #3	$114.55	3.298%	$118.3279	$118.33	$118.35	$118.30
Purchase #4	$62.79	11.705%	$70.1396	$70.14	$70.15	$70.10
Purchase #5	$71.99	12.864%	$81.2508	$81.25	$81.25	$81.30
Purchase #6	$102.67	8.538%	$111.436	$111.44	$111.45	$111.40
Purchase #7	$142.51	8.330%	$154.3811	$154.38	$154.40	$154.40
7 purchase totals =	$626.02		$675.3396	$675.34	$675.40	$675.40