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	$119.54	6.712%	$127.5635	$127.56	$127.55	$127.60
Purchase #2	$27.43	5.396%	$28.9101	$28.91	$28.90	$28.90
Purchase #3	$95.55	3.822%	$99.2019	$99.20	$99.20	$99.20
Purchase #4	$153.94	8.831%	$167.5344	$167.53	$167.55	$167.50
Purchase #5	$170.53	11.228%	$189.6771	$189.68	$189.70	$189.70
Purchase #6	$89.92	5.460%	$94.8296	$94.83	$94.85	$94.80
Purchase #7	$73.52	6.502%	$78.3003	$78.30	$78.30	$78.30
7 purchase totals =	$730.43		$786.0169	$786.01	$786.05	$786.00