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	$219.63	8.283%	$237.822	$237.82	$237.80	$237.80
Purchase #2	$50.75	8.644%	$55.1368	$55.14	$55.15	$55.10
Purchase #3	$200.74	8.172%	$217.1445	$217.14	$217.15	$217.10
Purchase #4	$87.40	13.553%	$99.2453	$99.25	$99.25	$99.20
Purchase #5	$88.56	3.273%	$91.4586	$91.46	$91.45	$91.50
Purchase #6	$218.63	3.769%	$226.8702	$226.87	$226.85	$226.90
Purchase #7	$119.82	11.382%	$133.4579	$133.46	$133.45	$133.50
7 purchase totals =	$985.53		$1,061.1353	$1,061.14	$1,061.10	$1,061.10