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	$66.51	9.383%	$72.7506	$72.75	$72.75	$72.80
Purchase #2	$183.37	5.232%	$192.9639	$192.96	$192.95	$193.00
Purchase #3	$204.88	11.710%	$228.8714	$228.87	$228.85	$228.90
Purchase #4	$94.75	7.505%	$101.861	$101.86	$101.85	$101.90
Purchase #5	$53.36	12.176%	$59.8571	$59.86	$59.85	$59.90
Purchase #6	$211.98	5.712%	$224.0883	$224.09	$224.10	$224.10
Purchase #7	$117.73	8.405%	$127.6252	$127.63	$127.65	$127.60
7 purchase totals =	$932.58		$1,008.0175	$1,008.02	$1,008.00	$1,008.20