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	$43.83	4.811%	$45.9387	$45.94	$45.95	$45.90
Purchase #2	$106.35	6.816%	$113.5988	$113.60	$113.60	$113.60
Purchase #3	$148.85	5.196%	$156.5842	$156.58	$156.60	$156.60
Purchase #4	$155.71	7.722%	$167.7339	$167.73	$167.75	$167.70
Purchase #5	$34.85	8.219%	$37.7143	$37.71	$37.70	$37.70
Purchase #6	$171.36	5.845%	$181.376	$181.38	$181.40	$181.40
Purchase #7	$83.36	12.830%	$94.0551	$94.06	$94.05	$94.10
7 purchase totals =	$744.31		$797.0010	$797.00	$797.05	$797.00