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	$208.70	5.493%	$220.1639	$220.16	$220.15	$220.20
Purchase #2	$41.50	5.401%	$43.7414	$43.74	$43.75	$43.70
Purchase #3	$45.44	6.464%	$48.3772	$48.38	$48.40	$48.40
Purchase #4	$122.65	11.344%	$136.5634	$136.56	$136.55	$136.60
Purchase #5	$230.28	11.244%	$256.1727	$256.17	$256.15	$256.20
Purchase #6	$118.90	8.138%	$128.5761	$128.58	$128.60	$128.60
Purchase #7	$212.25	7.573%	$228.3237	$228.32	$228.30	$228.30
7 purchase totals =	$979.72		$1,061.9184	$1,061.91	$1,061.90	$1,062.00