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	$105.25	12.120%	$118.0063	$118.01	$118.00	$118.00
Purchase #2	$98.42	5.126%	$103.465	$103.47	$103.45	$103.50
Purchase #3	$66.32	9.719%	$72.7656	$72.77	$72.75	$72.80
Purchase #4	$67.65	5.566%	$71.4154	$71.42	$71.40	$71.40
Purchase #5	$38.93	10.831%	$43.1465	$43.15	$43.15	$43.10
Purchase #6	$24.45	9.336%	$26.7327	$26.73	$26.75	$26.70
Purchase #7	$35.57	4.412%	$37.1393	$37.14	$37.15	$37.10
7 purchase totals =	$436.59		$472.6708	$472.69	$472.65	$472.60