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	$92.29	3.418%	$95.4445	$95.44	$95.45	$95.40
Purchase #2	$6.57	8.245%	$7.1117	$7.11	$7.10	$7.10
Purchase #3	$41.28	3.170%	$42.5886	$42.59	$42.60	$42.60
Purchase #4	$137.82	4.665%	$144.2493	$144.25	$144.25	$144.20
Purchase #5	$250.61	6.374%	$266.5839	$266.58	$266.60	$266.60
Purchase #6	$221.27	5.688%	$233.8558	$233.86	$233.85	$233.90
Purchase #7	$117.50	4.704%	$123.0272	$123.03	$123.05	$123.00
7 purchase totals =	$867.34		$912.8610	$912.86	$912.90	$912.80