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	$198.29	7.718%	$213.594	$213.59	$213.60	$213.60
Purchase #2	$238.53	12.867%	$269.2217	$269.22	$269.20	$269.20
Purchase #3	$184.29	3.317%	$190.4029	$190.40	$190.40	$190.40
Purchase #4	$219.64	9.325%	$240.1214	$240.12	$240.10	$240.10
Purchase #5	$27.54	6.318%	$29.28	$29.28	$29.30	$29.30
Purchase #6	$11.45	3.230%	$11.8198	$11.82	$11.80	$11.80
Purchase #7	$92.49	7.491%	$99.4184	$99.42	$99.40	$99.40
7 purchase totals =	$972.23		$1,053.8582	$1,053.85	$1,053.80	$1,053.80