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	$47.37	10.193%	$52.1984	$52.20	$52.20	$52.20
Purchase #2	$134.82	5.142%	$141.7524	$141.75	$141.75	$141.80
Purchase #3	$180.42	3.443%	$186.6319	$186.63	$186.65	$186.60
Purchase #4	$190.42	7.338%	$204.393	$204.39	$204.40	$204.40
Purchase #5	$217.44	12.476%	$244.5678	$244.57	$244.55	$244.60
Purchase #6	$123.25	7.360%	$132.3212	$132.32	$132.30	$132.30
Purchase #7	$51.74	5.388%	$54.5278	$54.53	$54.55	$54.50
7 purchase totals =	$945.46		$1,016.3925	$1,016.39	$1,016.40	$1,016.40