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	$224.90	5.859%	$238.0769	$238.08	$238.10	$238.10
Purchase #2	$9.97	3.672%	$10.3361	$10.34	$10.35	$10.30
Purchase #3	$34.95	11.361%	$38.9207	$38.92	$38.90	$38.90
Purchase #4	$82.88	6.723%	$88.452	$88.45	$88.45	$88.50
Purchase #5	$68.74	6.184%	$72.9909	$72.99	$73.00	$73.00
Purchase #6	$85.66	10.317%	$94.4975	$94.50	$94.50	$94.50
Purchase #7	$199.26	11.718%	$222.6093	$222.61	$222.60	$222.60
7 purchase totals =	$706.36		$765.8834	$765.89	$765.90	$765.90