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	$193.94	8.220%	$209.8819	$209.88	$209.90	$209.90
Purchase #2	$123.61	3.122%	$127.4691	$127.47	$127.45	$127.50
Purchase #3	$22.81	13.807%	$25.9594	$25.96	$25.95	$26.00
Purchase #4	$72.59	8.334%	$78.6397	$78.64	$78.65	$78.60
Purchase #5	$203.66	11.453%	$226.9852	$226.99	$227.00	$227.00
Purchase #6	$104.32	12.214%	$117.0616	$117.06	$117.05	$117.10
Purchase #7	$188.32	13.860%	$214.4212	$214.42	$214.40	$214.40
7 purchase totals =	$909.25		$1,000.4181	$1,000.42	$1,000.40	$1,000.50