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	$214.34	8.712%	$233.0133	$233.01	$233.00	$233.00
Purchase #2	$55.94	13.559%	$63.5249	$63.52	$63.50	$63.50
Purchase #3	$133.54	4.191%	$139.1367	$139.14	$139.15	$139.10
Purchase #4	$138.64	8.346%	$150.2109	$150.21	$150.20	$150.20
Purchase #5	$140.27	9.168%	$153.13	$153.13	$153.15	$153.10
Purchase #6	$243.25	13.303%	$275.6095	$275.61	$275.60	$275.60
Purchase #7	$96.50	5.445%	$101.7544	$101.75	$101.75	$101.80
7 purchase totals =	$1,022.48		$1,116.3797	$1,116.37	$1,116.35	$1,116.30