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	$193.75	9.791%	$212.7201	$212.72	$212.70	$212.70
Purchase #2	$93.90	7.278%	$100.734	$100.73	$100.75	$100.70
Purchase #3	$27.29	5.606%	$28.8199	$28.82	$28.80	$28.80
Purchase #4	$248.79	13.769%	$283.0459	$283.05	$283.05	$283.00
Purchase #5	$28.50	12.810%	$32.1509	$32.15	$32.15	$32.20
Purchase #6	$37.92	6.600%	$40.4227	$40.42	$40.40	$40.40
Purchase #7	$237.57	6.761%	$253.6321	$253.63	$253.65	$253.60
7 purchase totals =	$867.72		$951.5256	$951.52	$951.50	$951.40