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	$225.84	12.265%	$253.5393	$253.54	$253.55	$253.50
Purchase #2	$205.30	4.869%	$215.2961	$215.30	$215.30	$215.30
Purchase #3	$86.89	10.371%	$95.9014	$95.90	$95.90	$95.90
Purchase #4	$69.97	4.213%	$72.9178	$72.92	$72.90	$72.90
Purchase #5	$146.56	11.477%	$163.3807	$163.38	$163.40	$163.40
Purchase #6	$145.87	7.364%	$156.6119	$156.61	$156.60	$156.60
Purchase #7	$148.42	3.789%	$154.0436	$154.04	$154.05	$154.00
7 purchase totals =	$1,028.85		$1,111.6908	$1,111.69	$1,111.70	$1,111.60