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	$44.86	3.287%	$46.3345	$46.33	$46.35	$46.30
Purchase #2	$183.93	8.135%	$198.8927	$198.89	$198.90	$198.90
Purchase #3	$147.46	12.102%	$165.3056	$165.31	$165.30	$165.30
Purchase #4	$203.64	7.492%	$218.8967	$218.90	$218.90	$218.90
Purchase #5	$129.39	10.633%	$143.148	$143.15	$143.15	$143.10
Purchase #6	$9.44	12.548%	$10.6245	$10.62	$10.60	$10.60
Purchase #7	$162.73	10.269%	$179.4407	$179.44	$179.45	$179.40
7 purchase totals =	$881.45		$962.6427	$962.64	$962.65	$962.50