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	$204.57	4.463%	$213.7	$213.70	$213.70	$213.70
Purchase #2	$54.27	9.558%	$59.4571	$59.46	$59.45	$59.50
Purchase #3	$48.26	8.558%	$52.3901	$52.39	$52.40	$52.40
Purchase #4	$225.55	9.327%	$246.587	$246.59	$246.60	$246.60
Purchase #5	$109.88	5.836%	$116.2926	$116.29	$116.30	$116.30
Purchase #6	$150.59	3.280%	$155.5294	$155.53	$155.55	$155.50
Purchase #7	$237.55	13.589%	$269.8307	$269.83	$269.85	$269.80
7 purchase totals =	$1,030.67		$1,113.7869	$1,113.79	$1,113.85	$1,113.80