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	$232.80	5.494%	$245.59	$245.59	$245.60	$245.60
Purchase #2	$55.97	5.827%	$59.2314	$59.23	$59.25	$59.20
Purchase #3	$34.93	4.740%	$36.5857	$36.59	$36.60	$36.60
Purchase #4	$239.50	9.493%	$262.2357	$262.24	$262.25	$262.20
Purchase #5	$85.89	4.402%	$89.6709	$89.67	$89.65	$89.70
Purchase #6	$167.58	9.733%	$183.8906	$183.89	$183.90	$183.90
Purchase #7	$138.27	13.155%	$156.4594	$156.46	$156.45	$156.50
7 purchase totals =	$954.94		$1,033.6637	$1,033.67	$1,033.70	$1,033.70