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	$184.25	8.252%	$199.4543	$199.45	$199.45	$199.50
Purchase #2	$224.69	13.314%	$254.6052	$254.61	$254.60	$254.60
Purchase #3	$19.44	8.341%	$21.0615	$21.06	$21.05	$21.10
Purchase #4	$227.73	7.821%	$245.5408	$245.54	$245.55	$245.50
Purchase #5	$80.88	12.642%	$91.1048	$91.10	$91.10	$91.10
Purchase #6	$103.57	9.481%	$113.3895	$113.39	$113.40	$113.40
Purchase #7	$130.72	12.228%	$146.7044	$146.70	$146.70	$146.70
7 purchase totals =	$971.28		$1,071.8605	$1,071.85	$1,071.85	$1,071.90