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	$111.61	12.868%	$125.972	$125.97	$125.95	$126.00
Purchase #2	$133.55	6.789%	$142.6167	$142.62	$142.60	$142.60
Purchase #3	$25.47	10.452%	$28.1321	$28.13	$28.15	$28.10
Purchase #4	$211.48	3.455%	$218.7866	$218.79	$218.80	$218.80
Purchase #5	$227.50	12.698%	$256.388	$256.39	$256.40	$256.40
Purchase #6	$83.51	7.360%	$89.6563	$89.66	$89.65	$89.70
Purchase #7	$180.89	6.451%	$192.5592	$192.56	$192.55	$192.60
7 purchase totals =	$974.01		$1,054.1109	$1,054.12	$1,054.10	$1,054.20