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	$83.64	3.222%	$86.3349	$86.33	$86.35	$86.30
Purchase #2	$123.33	6.277%	$131.0714	$131.07	$131.05	$131.10
Purchase #3	$134.76	11.665%	$150.4798	$150.48	$150.50	$150.50
Purchase #4	$215.78	11.583%	$240.7738	$240.77	$240.75	$240.80
Purchase #5	$31.37	5.381%	$33.058	$33.06	$33.05	$33.10
Purchase #6	$109.38	10.205%	$120.5422	$120.54	$120.55	$120.50
Purchase #7	$123.82	7.216%	$132.7549	$132.75	$132.75	$132.80
7 purchase totals =	$822.08		$895.0150	$895.00	$895.00	$895.10