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	$126.26	5.430%	$133.1159	$133.12	$133.10	$133.10
Purchase #2	$96.38	9.149%	$105.1978	$105.20	$105.20	$105.20
Purchase #3	$140.85	5.300%	$148.3151	$148.32	$148.30	$148.30
Purchase #4	$163.26	7.155%	$174.9413	$174.94	$174.95	$174.90
Purchase #5	$180.91	13.564%	$205.4486	$205.45	$205.45	$205.40
Purchase #6	$203.64	9.829%	$223.6558	$223.66	$223.65	$223.70
Purchase #7	$105.39	5.511%	$111.198	$111.20	$111.20	$111.20
7 purchase totals =	$1,016.69		$1,101.8725	$1,101.89	$1,101.85	$1,101.80