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	$191.41	8.404%	$207.4961	$207.50	$207.50	$207.50
Purchase #2	$33.38	5.593%	$35.2469	$35.25	$35.25	$35.20
Purchase #3	$91.55	13.848%	$104.2278	$104.23	$104.25	$104.20
Purchase #4	$234.57	3.448%	$242.658	$242.66	$242.65	$242.70
Purchase #5	$174.82	12.519%	$196.7057	$196.71	$196.70	$196.70
Purchase #6	$146.62	10.800%	$162.455	$162.46	$162.45	$162.50
Purchase #7	$144.79	5.549%	$152.8244	$152.82	$152.80	$152.80
7 purchase totals =	$1,017.14		$1,101.6139	$1,101.63	$1,101.60	$1,101.60