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	$61.37	5.279%	$64.6097	$64.61	$64.60	$64.60
Purchase #2	$160.77	5.574%	$169.7313	$169.73	$169.75	$169.70
Purchase #3	$132.94	9.829%	$146.0067	$146.01	$146.00	$146.00
Purchase #4	$212.83	9.837%	$233.7661	$233.77	$233.75	$233.80
Purchase #5	$166.46	8.850%	$181.1917	$181.19	$181.20	$181.20
Purchase #6	$169.36	12.459%	$190.4606	$190.46	$190.45	$190.50
Purchase #7	$36.79	8.324%	$39.8524	$39.85	$39.85	$39.90
7 purchase totals =	$940.52		$1,025.6185	$1,025.62	$1,025.60	$1,025.70