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	$219.76	12.616%	$247.4849	$247.48	$247.50	$247.50
Purchase #2	$95.77	3.397%	$99.0233	$99.02	$99.00	$99.00
Purchase #3	$67.78	5.429%	$71.4598	$71.46	$71.45	$71.50
Purchase #4	$26.53	8.808%	$28.8668	$28.87	$28.85	$28.90
Purchase #5	$163.61	3.699%	$169.6619	$169.66	$169.65	$169.70
Purchase #6	$164.86	9.128%	$179.9084	$179.91	$179.90	$179.90
Purchase #7	$214.64	12.334%	$241.1137	$241.11	$241.10	$241.10
7 purchase totals =	$952.95		$1,037.5188	$1,037.51	$1,037.45	$1,037.60