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	$195.82	10.310%	$216.009	$216.01	$216.00	$216.00
Purchase #2	$236.57	8.103%	$255.7393	$255.74	$255.75	$255.70
Purchase #3	$54.29	5.737%	$57.4046	$57.40	$57.40	$57.40
Purchase #4	$95.53	10.139%	$105.2158	$105.22	$105.20	$105.20
Purchase #5	$59.69	5.608%	$63.0374	$63.04	$63.05	$63.00
Purchase #6	$200.34	11.167%	$222.712	$222.71	$222.70	$222.70
Purchase #7	$243.33	13.486%	$276.1455	$276.15	$276.15	$276.10
7 purchase totals =	$1,085.57		$1,196.2636	$1,196.27	$1,196.25	$1,196.10