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	$248.61	9.672%	$272.6556	$272.66	$272.65	$272.70
Purchase #2	$32.43	4.505%	$33.891	$33.89	$33.90	$33.90
Purchase #3	$160.30	3.492%	$165.8977	$165.90	$165.90	$165.90
Purchase #4	$214.37	4.792%	$224.6426	$224.64	$224.65	$224.60
Purchase #5	$148.71	10.650%	$164.5476	$164.55	$164.55	$164.50
Purchase #6	$142.68	11.684%	$159.3507	$159.35	$159.35	$159.40
Purchase #7	$217.46	11.286%	$242.0025	$242.00	$242.00	$242.00
7 purchase totals =	$1,164.56		$1,262.9877	$1,262.99	$1,263.00	$1,263.00