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	$103.94	7.527%	$111.7636	$111.76	$111.75	$111.80
Purchase #2	$14.38	5.124%	$15.1168	$15.12	$15.10	$15.10
Purchase #3	$100.71	4.354%	$105.0949	$105.09	$105.10	$105.10
Purchase #4	$233.54	13.189%	$264.3416	$264.34	$264.35	$264.30
Purchase #5	$148.70	9.191%	$162.367	$162.37	$162.35	$162.40
Purchase #6	$115.47	9.778%	$126.7607	$126.76	$126.75	$126.80
Purchase #7	$171.69	6.275%	$182.4635	$182.46	$182.45	$182.50
7 purchase totals =	$888.43		$967.9081	$967.90	$967.85	$968.00