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	$196.45	11.547%	$219.1341	$219.13	$219.15	$219.10
Purchase #2	$12.62	9.802%	$13.857	$13.86	$13.85	$13.90
Purchase #3	$223.75	7.433%	$240.3813	$240.38	$240.40	$240.40
Purchase #4	$232.47	9.872%	$255.4194	$255.42	$255.40	$255.40
Purchase #5	$76.75	12.724%	$86.5157	$86.52	$86.50	$86.50
Purchase #6	$29.28	8.671%	$31.8189	$31.82	$31.80	$31.80
Purchase #7	$209.98	9.356%	$229.6257	$229.63	$229.65	$229.60
7 purchase totals =	$981.30		$1,076.7521	$1,076.76	$1,076.75	$1,076.70