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	$95.28	11.606%	$106.3382	$106.34	$106.35	$106.30
Purchase #2	$205.60	8.176%	$222.4099	$222.41	$222.40	$222.40
Purchase #3	$210.33	8.473%	$228.1513	$228.15	$228.15	$228.20
Purchase #4	$59.67	3.148%	$61.5484	$61.55	$61.55	$61.50
Purchase #5	$100.57	12.244%	$112.8838	$112.88	$112.90	$112.90
Purchase #6	$16.53	6.216%	$17.5575	$17.56	$17.55	$17.60
Purchase #7	$248.34	3.425%	$256.8456	$256.85	$256.85	$256.80
7 purchase totals =	$936.32		$1,005.7347	$1,005.74	$1,005.75	$1,005.70