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	$88.67	4.435%	$92.6025	$92.60	$92.60	$92.60
Purchase #2	$116.74	6.551%	$124.3876	$124.39	$124.40	$124.40
Purchase #3	$206.39	6.429%	$219.6588	$219.66	$219.65	$219.70
Purchase #4	$243.76	8.728%	$265.0354	$265.04	$265.05	$265.00
Purchase #5	$94.92	5.133%	$99.7922	$99.79	$99.80	$99.80
Purchase #6	$136.62	8.663%	$148.4554	$148.46	$148.45	$148.50
Purchase #7	$127.87	6.771%	$136.5281	$136.53	$136.55	$136.50
7 purchase totals =	$1,014.97		$1,086.4600	$1,086.47	$1,086.50	$1,086.50