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	$88.38	7.526%	$95.0315	$95.03	$95.05	$95.00
Purchase #2	$122.99	4.594%	$128.6402	$128.64	$128.65	$128.60
Purchase #3	$137.78	7.851%	$148.5971	$148.60	$148.60	$148.60
Purchase #4	$33.95	13.570%	$38.557	$38.56	$38.55	$38.60
Purchase #5	$82.96	4.739%	$86.8915	$86.89	$86.90	$86.90
Purchase #6	$233.74	9.327%	$255.5409	$255.54	$255.55	$255.50
Purchase #7	$106.82	3.841%	$110.923	$110.92	$110.90	$110.90
7 purchase totals =	$806.62		$864.1812	$864.18	$864.20	$864.10