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	$162.89	5.354%	$171.6111	$171.61	$171.60	$171.60
Purchase #2	$19.71	9.545%	$21.5913	$21.59	$21.60	$21.60
Purchase #3	$53.53	6.537%	$57.0293	$57.03	$57.05	$57.00
Purchase #4	$245.78	5.580%	$259.4945	$259.49	$259.50	$259.50
Purchase #5	$187.28	3.178%	$193.2318	$193.23	$193.25	$193.20
Purchase #6	$247.36	6.746%	$264.0469	$264.05	$264.05	$264.00
Purchase #7	$131.32	5.519%	$138.5676	$138.57	$138.55	$138.60
7 purchase totals =	$1,047.87		$1,105.5725	$1,105.57	$1,105.60	$1,105.50