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	$141.98	8.791%	$154.4615	$154.46	$154.45	$154.50
Purchase #2	$217.52	4.500%	$227.3084	$227.31	$227.30	$227.30
Purchase #3	$197.97	13.857%	$225.4027	$225.40	$225.40	$225.40
Purchase #4	$143.68	9.724%	$157.6514	$157.65	$157.65	$157.70
Purchase #5	$100.50	8.794%	$109.338	$109.34	$109.35	$109.30
Purchase #6	$86.38	3.316%	$89.2444	$89.24	$89.25	$89.20
Purchase #7	$89.35	7.364%	$95.9297	$95.93	$95.95	$95.90
7 purchase totals =	$977.38		$1,059.3361	$1,059.33	$1,059.35	$1,059.30