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	$214.82	6.756%	$229.3332	$229.33	$229.35	$229.30
Purchase #2	$91.57	4.398%	$95.5972	$95.60	$95.60	$95.60
Purchase #3	$46.56	3.681%	$48.2739	$48.27	$48.25	$48.30
Purchase #4	$102.87	4.499%	$107.4981	$107.50	$107.50	$107.50
Purchase #5	$192.30	7.293%	$206.3244	$206.32	$206.30	$206.30
Purchase #6	$10.54	7.864%	$11.3689	$11.37	$11.35	$11.40
Purchase #7	$66.72	7.109%	$71.4631	$71.46	$71.45	$71.50
7 purchase totals =	$725.38		$769.8588	$769.85	$769.80	$769.90