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	$83.82	3.630%	$86.8627	$86.86	$86.85	$86.90
Purchase #2	$198.95	5.293%	$209.4804	$209.48	$209.50	$209.50
Purchase #3	$147.98	6.627%	$157.7866	$157.79	$157.80	$157.80
Purchase #4	$85.31	5.475%	$89.9807	$89.98	$90.00	$90.00
Purchase #5	$99.82	13.689%	$113.4844	$113.48	$113.50	$113.50
Purchase #6	$179.92	7.123%	$192.7357	$192.74	$192.75	$192.70
Purchase #7	$228.37	12.422%	$256.7381	$256.74	$256.75	$256.70
7 purchase totals =	$1,024.17		$1,107.0686	$1,107.07	$1,107.15	$1,107.10