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	$211.44	5.423%	$222.9064	$222.91	$222.90	$222.90
Purchase #2	$129.96	10.503%	$143.6097	$143.61	$143.60	$143.60
Purchase #3	$8.27	6.345%	$8.7947	$8.79	$8.80	$8.80
Purchase #4	$141.64	11.603%	$158.0745	$158.07	$158.05	$158.10
Purchase #5	$95.86	10.533%	$105.9569	$105.96	$105.95	$106.00
Purchase #6	$189.57	11.712%	$211.7724	$211.77	$211.75	$211.80
Purchase #7	$221.92	6.261%	$235.8144	$235.81	$235.80	$235.80
7 purchase totals =	$998.66		$1,086.9290	$1,086.92	$1,086.85	$1,087.00