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	$169.25	7.462%	$181.8794	$181.88	$181.90	$181.90
Purchase #2	$165.32	5.735%	$174.8011	$174.80	$174.80	$174.80
Purchase #3	$64.49	6.177%	$68.4735	$68.47	$68.45	$68.50
Purchase #4	$131.65	11.113%	$146.2803	$146.28	$146.30	$146.30
Purchase #5	$113.40	12.668%	$127.7655	$127.77	$127.75	$127.80
Purchase #6	$163.96	7.519%	$176.2882	$176.29	$176.30	$176.30
Purchase #7	$186.39	5.613%	$196.8521	$196.85	$196.85	$196.90
7 purchase totals =	$994.46		$1,072.3401	$1,072.34	$1,072.35	$1,072.50