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	$217.94	4.197%	$227.0869	$227.09	$227.10	$227.10
Purchase #2	$80.95	11.328%	$90.12	$90.12	$90.10	$90.10
Purchase #3	$176.96	11.119%	$196.6362	$196.64	$196.65	$196.60
Purchase #4	$243.90	12.194%	$273.6412	$273.64	$273.65	$273.60
Purchase #5	$6.85	12.485%	$7.7052	$7.71	$7.70	$7.70
Purchase #6	$87.31	8.832%	$95.0212	$95.02	$95.00	$95.00
Purchase #7	$134.83	5.210%	$141.8546	$141.85	$141.85	$141.90
7 purchase totals =	$948.74		$1,032.0653	$1,032.07	$1,032.05	$1,032.00