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	$57.29	9.309%	$62.6231	$62.62	$62.60	$62.60
Purchase #2	$118.25	5.839%	$125.1546	$125.15	$125.15	$125.20
Purchase #3	$110.27	8.634%	$119.7907	$119.79	$119.80	$119.80
Purchase #4	$96.28	4.831%	$100.9313	$100.93	$100.95	$100.90
Purchase #5	$85.97	11.555%	$95.9038	$95.90	$95.90	$95.90
Purchase #6	$110.84	11.332%	$123.4004	$123.40	$123.40	$123.40
Purchase #7	$69.81	4.336%	$72.837	$72.84	$72.85	$72.80
7 purchase totals =	$648.71		$700.6409	$700.63	$700.65	$700.60