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	$214.52	12.617%	$241.586	$241.59	$241.60	$241.60
Purchase #2	$226.61	6.157%	$240.5624	$240.56	$240.55	$240.60
Purchase #3	$17.26	8.527%	$18.7318	$18.73	$18.75	$18.70
Purchase #4	$185.91	5.120%	$195.4286	$195.43	$195.45	$195.40
Purchase #5	$85.48	11.814%	$95.5786	$95.58	$95.60	$95.60
Purchase #6	$47.93	9.721%	$52.5893	$52.59	$52.60	$52.60
Purchase #7	$174.47	6.343%	$185.5366	$185.54	$185.55	$185.50
7 purchase totals =	$952.18		$1,030.0133	$1,030.02	$1,030.10	$1,030.00