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	$83.47	10.184%	$91.9706	$91.97	$91.95	$92.00
Purchase #2	$117.55	9.656%	$128.9006	$128.90	$128.90	$128.90
Purchase #3	$153.83	5.504%	$162.2968	$162.30	$162.30	$162.30
Purchase #4	$88.95	8.212%	$96.2546	$96.25	$96.25	$96.30
Purchase #5	$249.91	12.111%	$280.1766	$280.18	$280.20	$280.20
Purchase #6	$89.94	4.769%	$94.2292	$94.23	$94.25	$94.20
Purchase #7	$174.67	9.716%	$191.6409	$191.64	$191.65	$191.60
7 purchase totals =	$958.32		$1,045.4693	$1,045.47	$1,045.50	$1,045.50