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	$234.56	11.693%	$261.9871	$261.99	$262.00	$262.00
Purchase #2	$19.69	4.266%	$20.53	$20.53	$20.55	$20.50
Purchase #3	$198.59	7.486%	$213.4564	$213.46	$213.45	$213.50
Purchase #4	$92.42	7.692%	$99.5289	$99.53	$99.55	$99.50
Purchase #5	$213.49	6.219%	$226.7669	$226.77	$226.75	$226.80
Purchase #6	$156.81	7.484%	$168.5457	$168.55	$168.55	$168.50
Purchase #7	$46.69	12.466%	$52.5104	$52.51	$52.50	$52.50
7 purchase totals =	$962.25		$1,043.3254	$1,043.34	$1,043.35	$1,043.30