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	$217.88	7.228%	$233.6284	$233.63	$233.65	$233.60
Purchase #2	$87.82	7.766%	$94.6401	$94.64	$94.65	$94.60
Purchase #3	$52.32	4.176%	$54.5049	$54.50	$54.50	$54.50
Purchase #4	$233.62	13.187%	$264.4275	$264.43	$264.45	$264.40
Purchase #5	$141.82	7.643%	$152.6593	$152.66	$152.65	$152.70
Purchase #6	$121.25	11.107%	$134.7172	$134.72	$134.70	$134.70
Purchase #7	$143.38	9.416%	$156.8807	$156.88	$156.90	$156.90
7 purchase totals =	$998.09		$1,091.4581	$1,091.46	$1,091.50	$1,091.40