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	$180.76	8.772%	$196.6163	$196.62	$196.60	$196.60
Purchase #2	$12.85	5.579%	$13.5669	$13.57	$13.55	$13.60
Purchase #3	$186.48	8.228%	$201.8236	$201.82	$201.80	$201.80
Purchase #4	$249.60	9.307%	$272.8303	$272.83	$272.85	$272.80
Purchase #5	$116.73	9.591%	$127.9256	$127.93	$127.95	$127.90
Purchase #6	$204.27	12.735%	$230.2838	$230.28	$230.30	$230.30
Purchase #7	$64.61	5.527%	$68.181	$68.18	$68.20	$68.20
7 purchase totals =	$1,015.30		$1,111.2275	$1,111.23	$1,111.25	$1,111.20