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	$228.57	5.869%	$241.9848	$241.98	$242.00	$242.00
Purchase #2	$20.52	10.379%	$22.6498	$22.65	$22.65	$22.60
Purchase #3	$239.98	7.330%	$257.5705	$257.57	$257.55	$257.60
Purchase #4	$192.89	3.799%	$200.2179	$200.22	$200.20	$200.20
Purchase #5	$55.88	3.163%	$57.6475	$57.65	$57.65	$57.60
Purchase #6	$143.37	13.154%	$162.2289	$162.23	$162.25	$162.20
Purchase #7	$66.48	7.686%	$71.5897	$71.59	$71.60	$71.60
7 purchase totals =	$947.69		$1,013.8891	$1,013.89	$1,013.90	$1,013.80