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	$82.36	4.353%	$85.9451	$85.95	$85.95	$85.90
Purchase #2	$34.86	10.240%	$38.4297	$38.43	$38.45	$38.40
Purchase #3	$245.64	10.659%	$271.8228	$271.82	$271.80	$271.80
Purchase #4	$216.53	4.784%	$226.8888	$226.89	$226.90	$226.90
Purchase #5	$117.91	3.333%	$121.8399	$121.84	$121.85	$121.80
Purchase #6	$81.51	4.677%	$85.3222	$85.32	$85.30	$85.30
Purchase #7	$248.86	13.233%	$281.7916	$281.79	$281.80	$281.80
7 purchase totals =	$1,027.67		$1,112.0401	$1,112.04	$1,112.05	$1,111.90