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	$163.47	9.467%	$178.9457	$178.95	$178.95	$178.90
Purchase #2	$116.46	3.126%	$120.1005	$120.10	$120.10	$120.10
Purchase #3	$52.39	4.801%	$54.9052	$54.91	$54.90	$54.90
Purchase #4	$138.41	10.278%	$152.6358	$152.64	$152.65	$152.60
Purchase #5	$96.56	9.840%	$106.0615	$106.06	$106.05	$106.10
Purchase #6	$123.28	13.561%	$139.998	$140.00	$140.00	$140.00
Purchase #7	$249.45	6.481%	$265.6169	$265.62	$265.60	$265.60
7 purchase totals =	$940.02		$1,018.2636	$1,018.28	$1,018.25	$1,018.20