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	$179.41	5.873%	$189.9467	$189.95	$189.95	$189.90
Purchase #2	$210.82	11.590%	$235.254	$235.25	$235.25	$235.30
Purchase #3	$88.47	7.730%	$95.3087	$95.31	$95.30	$95.30
Purchase #4	$23.83	6.862%	$25.4652	$25.47	$25.45	$25.50
Purchase #5	$190.54	5.274%	$200.5891	$200.59	$200.60	$200.60
Purchase #6	$94.66	3.592%	$98.0602	$98.06	$98.05	$98.10
Purchase #7	$189.89	8.619%	$206.2566	$206.26	$206.25	$206.30
7 purchase totals =	$977.62		$1,050.8805	$1,050.89	$1,050.85	$1,051.00