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	$174.52	13.412%	$197.9266	$197.93	$197.95	$197.90
Purchase #2	$222.61	13.176%	$251.9411	$251.94	$251.95	$251.90
Purchase #3	$51.48	5.508%	$54.3155	$54.32	$54.30	$54.30
Purchase #4	$180.72	6.116%	$191.7728	$191.77	$191.75	$191.80
Purchase #5	$39.80	4.306%	$41.5138	$41.51	$41.50	$41.50
Purchase #6	$17.60	13.728%	$20.0161	$20.02	$20.00	$20.00
Purchase #7	$177.65	10.592%	$196.4667	$196.47	$196.45	$196.50
7 purchase totals =	$864.38		$953.9526	$953.96	$953.90	$953.90