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	$76.48	9.502%	$83.7471	$83.75	$83.75	$83.70
Purchase #2	$86.82	12.683%	$97.8314	$97.83	$97.85	$97.80
Purchase #3	$112.77	5.737%	$119.2396	$119.24	$119.25	$119.20
Purchase #4	$207.84	7.109%	$222.6153	$222.62	$222.60	$222.60
Purchase #5	$175.95	3.394%	$181.9217	$181.92	$181.90	$181.90
Purchase #6	$162.45	9.865%	$178.4757	$178.48	$178.50	$178.50
Purchase #7	$124.50	13.745%	$141.6125	$141.61	$141.60	$141.60
7 purchase totals =	$946.81		$1,025.4433	$1,025.45	$1,025.45	$1,025.30