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	$245.98	3.819%	$255.374	$255.37	$255.35	$255.40
Purchase #2	$217.52	5.730%	$229.9839	$229.98	$230.00	$230.00
Purchase #3	$210.26	5.357%	$221.5236	$221.52	$221.50	$221.50
Purchase #4	$13.90	8.342%	$15.0595	$15.06	$15.05	$15.10
Purchase #5	$32.91	13.571%	$37.3762	$37.38	$37.40	$37.40
Purchase #6	$106.85	11.139%	$118.752	$118.75	$118.75	$118.80
Purchase #7	$176.35	4.740%	$184.709	$184.71	$184.70	$184.70
7 purchase totals =	$1,003.77		$1,062.7782	$1,062.77	$1,062.75	$1,062.90