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	$169.77	7.175%	$181.951	$181.95	$181.95	$182.00
Purchase #2	$139.30	6.214%	$147.9561	$147.96	$147.95	$148.00
Purchase #3	$172.83	3.438%	$178.7719	$178.77	$178.75	$178.80
Purchase #4	$229.69	5.691%	$242.7617	$242.76	$242.75	$242.80
Purchase #5	$66.82	8.792%	$72.6948	$72.69	$72.70	$72.70
Purchase #6	$196.65	11.715%	$219.6875	$219.69	$219.70	$219.70
Purchase #7	$212.82	4.542%	$222.4863	$222.49	$222.50	$222.50
7 purchase totals =	$1,187.88		$1,266.3093	$1,266.31	$1,266.30	$1,266.50