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	$222.60	3.810%	$231.0811	$231.08	$231.10	$231.10
Purchase #2	$96.83	5.112%	$101.7799	$101.78	$101.80	$101.80
Purchase #3	$13.87	6.596%	$14.7849	$14.78	$14.80	$14.80
Purchase #4	$142.39	6.221%	$151.2481	$151.25	$151.25	$151.20
Purchase #5	$19.77	6.742%	$21.1029	$21.10	$21.10	$21.10
Purchase #6	$197.49	10.676%	$218.574	$218.57	$218.55	$218.60
Purchase #7	$83.30	4.381%	$86.9494	$86.95	$86.95	$86.90
7 purchase totals =	$776.25		$825.5203	$825.51	$825.55	$825.50