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	$146.60	9.148%	$160.011	$160.01	$160.00	$160.00
Purchase #2	$41.92	8.407%	$45.4442	$45.44	$45.45	$45.40
Purchase #3	$133.39	10.410%	$147.2759	$147.28	$147.30	$147.30
Purchase #4	$133.32	8.256%	$144.3269	$144.33	$144.35	$144.30
Purchase #5	$221.50	10.322%	$244.3632	$244.36	$244.35	$244.40
Purchase #6	$157.53	7.429%	$169.2329	$169.23	$169.25	$169.20
Purchase #7	$118.31	13.643%	$134.451	$134.45	$134.45	$134.50
7 purchase totals =	$952.57		$1,045.1051	$1,045.10	$1,045.15	$1,045.10