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	$123.57	6.846%	$132.0296	$132.03	$132.05	$132.00
Purchase #2	$130.79	4.790%	$137.0548	$137.05	$137.05	$137.10
Purchase #3	$197.99	11.866%	$221.4835	$221.48	$221.50	$221.50
Purchase #4	$160.60	7.340%	$172.388	$172.39	$172.40	$172.40
Purchase #5	$97.91	11.185%	$108.8612	$108.86	$108.85	$108.90
Purchase #6	$233.40	13.390%	$264.6523	$264.65	$264.65	$264.70
Purchase #7	$104.83	10.575%	$115.9158	$115.92	$115.90	$115.90
7 purchase totals =	$1,049.09		$1,152.3852	$1,152.38	$1,152.40	$1,152.50