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	$172.73	10.596%	$191.0325	$191.03	$191.05	$191.00
Purchase #2	$134.52	12.443%	$151.2583	$151.26	$151.25	$151.30
Purchase #3	$14.63	13.730%	$16.6387	$16.64	$16.65	$16.60
Purchase #4	$35.86	8.555%	$38.9278	$38.93	$38.95	$38.90
Purchase #5	$63.98	13.524%	$72.6327	$72.63	$72.65	$72.60
Purchase #6	$114.94	4.185%	$119.7502	$119.75	$119.75	$119.80
Purchase #7	$92.39	13.845%	$105.1814	$105.18	$105.20	$105.20
7 purchase totals =	$629.05		$695.4216	$695.42	$695.50	$695.40