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	$146.27	4.293%	$152.5494	$152.55	$152.55	$152.50
Purchase #2	$193.75	11.231%	$215.5101	$215.51	$215.50	$215.50
Purchase #3	$199.78	6.382%	$212.53	$212.53	$212.55	$212.50
Purchase #4	$219.25	11.548%	$244.569	$244.57	$244.55	$244.60
Purchase #5	$34.85	5.298%	$36.6964	$36.70	$36.70	$36.70
Purchase #6	$52.55	5.412%	$55.394	$55.39	$55.40	$55.40
Purchase #7	$123.68	13.214%	$140.0231	$140.02	$140.00	$140.00
7 purchase totals =	$970.13		$1,057.2720	$1,057.27	$1,057.25	$1,057.20