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	$211.93	12.191%	$237.7664	$237.77	$237.75	$237.80
Purchase #2	$10.40	10.623%	$11.5048	$11.50	$11.50	$11.50
Purchase #3	$76.73	5.128%	$80.6647	$80.66	$80.65	$80.70
Purchase #4	$227.40	8.137%	$245.9035	$245.90	$245.90	$245.90
Purchase #5	$57.90	3.299%	$59.8101	$59.81	$59.80	$59.80
Purchase #6	$180.49	11.837%	$201.8546	$201.85	$201.85	$201.90
Purchase #7	$164.55	4.753%	$172.3711	$172.37	$172.35	$172.40
7 purchase totals =	$929.40		$1,009.8752	$1,009.86	$1,009.80	$1,010.00