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	$88.40	6.855%	$94.4598	$94.46	$94.45	$94.50
Purchase #2	$207.52	7.619%	$223.3309	$223.33	$223.35	$223.30
Purchase #3	$76.41	5.800%	$80.8418	$80.84	$80.85	$80.80
Purchase #4	$77.25	6.182%	$82.0256	$82.03	$82.05	$82.00
Purchase #5	$101.87	12.478%	$114.5813	$114.58	$114.60	$114.60
Purchase #6	$240.98	7.226%	$258.3932	$258.39	$258.40	$258.40
Purchase #7	$186.49	12.370%	$209.5588	$209.56	$209.55	$209.60
7 purchase totals =	$978.92		$1,063.1914	$1,063.19	$1,063.25	$1,063.20