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	$184.30	9.135%	$201.1358	$201.14	$201.15	$201.10
Purchase #2	$69.41	4.852%	$72.7778	$72.78	$72.80	$72.80
Purchase #3	$83.86	5.640%	$88.5897	$88.59	$88.60	$88.60
Purchase #4	$77.51	5.109%	$81.47	$81.47	$81.45	$81.50
Purchase #5	$39.32	8.167%	$42.5313	$42.53	$42.55	$42.50
Purchase #6	$145.69	3.444%	$150.7076	$150.71	$150.70	$150.70
Purchase #7	$177.80	11.184%	$197.6852	$197.69	$197.70	$197.70
7 purchase totals =	$777.89		$834.8974	$834.91	$834.95	$834.90