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	$183.61	13.729%	$208.8178	$208.82	$208.80	$208.80
Purchase #2	$241.90	7.122%	$259.1281	$259.13	$259.15	$259.10
Purchase #3	$204.30	9.504%	$223.7167	$223.72	$223.70	$223.70
Purchase #4	$152.89	3.674%	$158.5072	$158.51	$158.50	$158.50
Purchase #5	$12.92	5.637%	$13.6483	$13.65	$13.65	$13.60
Purchase #6	$100.71	3.773%	$104.5098	$104.51	$104.50	$104.50
Purchase #7	$149.83	9.801%	$164.5148	$164.51	$164.50	$164.50
7 purchase totals =	$1,046.16		$1,132.8427	$1,132.85	$1,132.80	$1,132.70