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	$213.48	6.542%	$227.4459	$227.45	$227.45	$227.40
Purchase #2	$188.40	6.612%	$200.857	$200.86	$200.85	$200.90
Purchase #3	$216.53	11.437%	$241.2945	$241.29	$241.30	$241.30
Purchase #4	$112.64	3.429%	$116.5024	$116.50	$116.50	$116.50
Purchase #5	$233.95	12.257%	$262.6253	$262.63	$262.65	$262.60
Purchase #6	$214.33	13.790%	$243.8861	$243.89	$243.90	$243.90
Purchase #7	$205.41	7.372%	$220.5528	$220.55	$220.55	$220.60
7 purchase totals =	$1,384.74		$1,513.1640	$1,513.17	$1,513.20	$1,513.20