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	$171.86	13.369%	$194.836	$194.84	$194.85	$194.80
Purchase #2	$185.85	6.227%	$197.4229	$197.42	$197.40	$197.40
Purchase #3	$133.52	4.422%	$139.4243	$139.42	$139.40	$139.40
Purchase #4	$183.96	6.870%	$196.5981	$196.60	$196.60	$196.60
Purchase #5	$54.31	5.649%	$57.378	$57.38	$57.40	$57.40
Purchase #6	$152.32	12.719%	$171.6936	$171.69	$171.70	$171.70
Purchase #7	$60.82	7.847%	$65.5925	$65.59	$65.60	$65.60
7 purchase totals =	$942.64		$1,022.9454	$1,022.94	$1,022.95	$1,022.90