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	$221.86	10.641%	$245.4681	$245.47	$245.45	$245.50
Purchase #2	$70.60	3.194%	$72.855	$72.86	$72.85	$72.90
Purchase #3	$141.86	8.784%	$154.321	$154.32	$154.30	$154.30
Purchase #4	$110.65	4.111%	$115.1988	$115.20	$115.20	$115.20
Purchase #5	$23.37	4.758%	$24.4819	$24.48	$24.50	$24.50
Purchase #6	$140.35	3.618%	$145.4279	$145.43	$145.45	$145.40
Purchase #7	$134.61	3.304%	$139.0575	$139.06	$139.05	$139.10
7 purchase totals =	$843.30		$896.8102	$896.82	$896.80	$896.90