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	$59.62	10.248%	$65.7299	$65.73	$65.75	$65.70
Purchase #2	$247.47	7.597%	$266.2703	$266.27	$266.25	$266.30
Purchase #3	$51.67	7.262%	$55.4223	$55.42	$55.40	$55.40
Purchase #4	$200.70	7.445%	$215.6421	$215.64	$215.65	$215.60
Purchase #5	$242.85	9.464%	$265.8333	$265.83	$265.85	$265.80
Purchase #6	$81.26	5.237%	$85.5156	$85.52	$85.50	$85.50
Purchase #7	$229.87	9.185%	$250.9836	$250.98	$251.00	$251.00
7 purchase totals =	$1,113.44		$1,205.3971	$1,205.39	$1,205.40	$1,205.30