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	$244.77	8.442%	$265.4335	$265.43	$265.45	$265.40
Purchase #2	$231.28	4.557%	$241.8194	$241.82	$241.80	$241.80
Purchase #3	$48.55	4.140%	$50.56	$50.56	$50.55	$50.60
Purchase #4	$218.48	13.184%	$247.2844	$247.28	$247.30	$247.30
Purchase #5	$64.30	8.625%	$69.8459	$69.85	$69.85	$69.80
Purchase #6	$52.27	13.636%	$59.3975	$59.40	$59.40	$59.40
Purchase #7	$82.77	11.659%	$92.4202	$92.42	$92.40	$92.40
7 purchase totals =	$942.42		$1,026.7609	$1,026.76	$1,026.75	$1,026.70