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	$233.60	9.796%	$256.4835	$256.48	$256.50	$256.50
Purchase #2	$116.66	9.694%	$127.969	$127.97	$127.95	$128.00
Purchase #3	$89.47	9.494%	$97.9643	$97.96	$97.95	$98.00
Purchase #4	$153.95	9.217%	$168.1396	$168.14	$168.15	$168.10
Purchase #5	$140.96	11.726%	$157.489	$157.49	$157.50	$157.50
Purchase #6	$78.64	4.129%	$81.887	$81.89	$81.90	$81.90
Purchase #7	$149.73	5.243%	$157.5803	$157.58	$157.60	$157.60
7 purchase totals =	$963.01		$1,047.5127	$1,047.51	$1,047.55	$1,047.60