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	$171.31	11.766%	$191.4663	$191.47	$191.45	$191.50
Purchase #2	$7.69	12.666%	$8.664	$8.66	$8.65	$8.70
Purchase #3	$46.28	10.795%	$51.2759	$51.28	$51.30	$51.30
Purchase #4	$12.33	8.693%	$13.4018	$13.40	$13.40	$13.40
Purchase #5	$66.76	9.124%	$72.8512	$72.85	$72.85	$72.90
Purchase #6	$142.38	9.248%	$155.5473	$155.55	$155.55	$155.50
Purchase #7	$182.47	5.201%	$191.9603	$191.96	$191.95	$192.00
7 purchase totals =	$629.22		$685.1668	$685.17	$685.15	$685.30