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	$215.77	5.643%	$227.9459	$227.95	$227.95	$227.90
Purchase #2	$145.82	13.618%	$165.6778	$165.68	$165.70	$165.70
Purchase #3	$106.77	4.298%	$111.359	$111.36	$111.35	$111.40
Purchase #4	$69.90	9.481%	$76.5272	$76.53	$76.55	$76.50
Purchase #5	$211.92	10.686%	$234.5658	$234.57	$234.55	$234.60
Purchase #6	$175.82	7.116%	$188.3314	$188.33	$188.35	$188.30
Purchase #7	$11.41	12.853%	$12.8765	$12.88	$12.90	$12.90
7 purchase totals =	$937.41		$1,017.2836	$1,017.30	$1,017.35	$1,017.30