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	$190.52	11.601%	$212.6222	$212.62	$212.60	$212.60
Purchase #2	$179.76	6.388%	$191.2431	$191.24	$191.25	$191.20
Purchase #3	$74.86	9.841%	$82.227	$82.23	$82.25	$82.20
Purchase #4	$114.32	5.433%	$120.531	$120.53	$120.55	$120.50
Purchase #5	$169.86	4.695%	$177.8349	$177.83	$177.85	$177.80
Purchase #6	$204.35	4.394%	$213.3291	$213.33	$213.35	$213.30
Purchase #7	$21.89	11.698%	$24.4507	$24.45	$24.45	$24.50
7 purchase totals =	$955.56		$1,022.2380	$1,022.23	$1,022.30	$1,022.10