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	$193.57	11.298%	$215.4395	$215.44	$215.45	$215.40
Purchase #2	$152.66	13.188%	$172.7928	$172.79	$172.80	$172.80
Purchase #3	$142.38	13.807%	$162.0384	$162.04	$162.05	$162.00
Purchase #4	$179.44	5.117%	$188.6219	$188.62	$188.60	$188.60
Purchase #5	$128.53	7.631%	$138.3381	$138.34	$138.35	$138.30
Purchase #6	$115.70	7.611%	$124.5059	$124.51	$124.50	$124.50
Purchase #7	$151.72	12.391%	$170.5196	$170.52	$170.50	$170.50
7 purchase totals =	$1,064.00		$1,172.2562	$1,172.26	$1,172.25	$1,172.10