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	$59.50	3.566%	$61.6218	$61.62	$61.60	$61.60
Purchase #2	$108.56	4.572%	$113.5234	$113.52	$113.50	$113.50
Purchase #3	$42.73	12.135%	$47.9153	$47.92	$47.90	$47.90
Purchase #4	$219.94	4.462%	$229.7537	$229.75	$229.75	$229.80
Purchase #5	$38.36	6.280%	$40.769	$40.77	$40.75	$40.80
Purchase #6	$43.35	6.702%	$46.2553	$46.26	$46.25	$46.30
Purchase #7	$219.27	3.322%	$226.5541	$226.55	$226.55	$226.60
7 purchase totals =	$731.71		$766.3926	$766.39	$766.30	$766.50