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	$73.71	3.176%	$76.051	$76.05	$76.05	$76.10
Purchase #2	$78.40	5.579%	$82.7739	$82.77	$82.75	$82.80
Purchase #3	$129.92	12.590%	$146.2769	$146.28	$146.30	$146.30
Purchase #4	$135.83	6.611%	$144.8097	$144.81	$144.80	$144.80
Purchase #5	$222.41	12.406%	$250.0022	$250.00	$250.00	$250.00
Purchase #6	$246.61	5.236%	$259.5225	$259.52	$259.50	$259.50
Purchase #7	$98.27	6.453%	$104.6114	$104.61	$104.60	$104.60
7 purchase totals =	$985.15		$1,064.0476	$1,064.04	$1,064.00	$1,064.10