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	$215.53	4.357%	$224.9206	$224.92	$224.90	$224.90
Purchase #2	$227.26	6.129%	$241.1888	$241.19	$241.20	$241.20
Purchase #3	$105.80	13.526%	$120.1105	$120.11	$120.10	$120.10
Purchase #4	$234.82	6.869%	$250.9498	$250.95	$250.95	$250.90
Purchase #5	$43.51	6.577%	$46.3717	$46.37	$46.35	$46.40
Purchase #6	$132.98	3.400%	$137.5013	$137.50	$137.50	$137.50
Purchase #7	$85.67	5.843%	$90.6757	$90.68	$90.70	$90.70
7 purchase totals =	$1,045.57		$1,111.7184	$1,111.72	$1,111.70	$1,111.70