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	$147.55	4.687%	$154.4657	$154.47	$154.45	$154.50
Purchase #2	$166.67	11.335%	$185.562	$185.56	$185.55	$185.60
Purchase #3	$199.25	7.837%	$214.8652	$214.87	$214.85	$214.90
Purchase #4	$145.30	7.825%	$156.6697	$156.67	$156.65	$156.70
Purchase #5	$164.48	6.726%	$175.5429	$175.54	$175.55	$175.50
Purchase #6	$98.72	6.248%	$104.888	$104.89	$104.90	$104.90
Purchase #7	$68.46	3.387%	$70.7787	$70.78	$70.80	$70.80
7 purchase totals =	$990.43		$1,062.7722	$1,062.78	$1,062.75	$1,062.90