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	$86.47	10.256%	$95.3384	$95.34	$95.35	$95.30
Purchase #2	$214.64	13.763%	$244.1809	$244.18	$244.20	$244.20
Purchase #3	$70.34	4.237%	$73.3203	$73.32	$73.30	$73.30
Purchase #4	$180.41	7.604%	$194.1284	$194.13	$194.15	$194.10
Purchase #5	$96.45	7.289%	$103.4802	$103.48	$103.50	$103.50
Purchase #6	$106.37	5.349%	$112.0597	$112.06	$112.05	$112.10
Purchase #7	$247.81	10.291%	$273.3121	$273.31	$273.30	$273.30
7 purchase totals =	$1,002.49		$1,095.8200	$1,095.82	$1,095.85	$1,095.80