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	$32.75	6.758%	$34.9632	$34.96	$34.95	$35.00
Purchase #2	$137.44	9.726%	$150.8074	$150.81	$150.80	$150.80
Purchase #3	$202.95	4.338%	$211.754	$211.75	$211.75	$211.80
Purchase #4	$242.68	5.186%	$255.2654	$255.27	$255.25	$255.30
Purchase #5	$113.29	8.708%	$123.1553	$123.16	$123.15	$123.20
Purchase #6	$215.70	13.487%	$244.7915	$244.79	$244.80	$244.80
Purchase #7	$150.56	11.313%	$167.5929	$167.59	$167.60	$167.60
7 purchase totals =	$1,095.37		$1,188.3297	$1,188.33	$1,188.30	$1,188.50