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	$194.27	10.437%	$214.546	$214.55	$214.55	$214.50
Purchase #2	$189.78	4.693%	$198.6864	$198.69	$198.70	$198.70
Purchase #3	$247.64	13.676%	$281.5072	$281.51	$281.50	$281.50
Purchase #4	$196.40	8.867%	$213.8148	$213.81	$213.80	$213.80
Purchase #5	$11.47	12.519%	$12.9059	$12.91	$12.90	$12.90
Purchase #6	$55.93	13.287%	$63.3614	$63.36	$63.35	$63.40
Purchase #7	$38.77	4.451%	$40.4957	$40.50	$40.50	$40.50
7 purchase totals =	$934.26		$1,025.3174	$1,025.33	$1,025.30	$1,025.30