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	$241.89	11.463%	$269.6179	$269.62	$269.60	$269.60
Purchase #2	$131.96	11.643%	$147.3241	$147.32	$147.30	$147.30
Purchase #3	$86.64	7.454%	$93.0981	$93.10	$93.10	$93.10
Purchase #4	$180.83	5.508%	$190.7901	$190.79	$190.80	$190.80
Purchase #5	$49.61	5.628%	$52.4021	$52.40	$52.40	$52.40
Purchase #6	$143.41	9.164%	$156.5521	$156.55	$156.55	$156.60
Purchase #7	$92.78	10.218%	$102.2603	$102.26	$102.25	$102.30
7 purchase totals =	$927.12		$1,012.0447	$1,012.04	$1,012.00	$1,012.10