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	$195.77	7.118%	$209.7049	$209.70	$209.70	$209.70
Purchase #2	$197.34	10.268%	$217.6029	$217.60	$217.60	$217.60
Purchase #3	$105.98	9.160%	$115.6878	$115.69	$115.70	$115.70
Purchase #4	$241.30	4.135%	$251.2778	$251.28	$251.30	$251.30
Purchase #5	$83.33	7.347%	$89.4523	$89.45	$89.45	$89.50
Purchase #6	$111.53	6.354%	$118.6166	$118.62	$118.60	$118.60
Purchase #7	$148.76	13.546%	$168.911	$168.91	$168.90	$168.90
7 purchase totals =	$1,084.01		$1,171.2533	$1,171.25	$1,171.25	$1,171.30