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	$171.63	7.752%	$184.9348	$184.93	$184.95	$184.90
Purchase #2	$175.32	6.132%	$186.0706	$186.07	$186.05	$186.10
Purchase #3	$38.47	8.104%	$41.5876	$41.59	$41.60	$41.60
Purchase #4	$136.49	6.452%	$145.2963	$145.30	$145.30	$145.30
Purchase #5	$168.76	3.333%	$174.3848	$174.38	$174.40	$174.40
Purchase #6	$95.47	4.416%	$99.686	$99.69	$99.70	$99.70
Purchase #7	$90.31	5.783%	$95.5326	$95.53	$95.55	$95.50
7 purchase totals =	$876.45		$927.4927	$927.49	$927.55	$927.50