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	$104.72	9.757%	$114.9375	$114.94	$114.95	$114.90
Purchase #2	$95.76	12.671%	$107.8937	$107.89	$107.90	$107.90
Purchase #3	$55.38	7.250%	$59.3951	$59.40	$59.40	$59.40
Purchase #4	$126.72	3.568%	$131.2414	$131.24	$131.25	$131.20
Purchase #5	$178.46	9.500%	$195.4137	$195.41	$195.40	$195.40
Purchase #6	$218.56	5.773%	$231.1775	$231.18	$231.20	$231.20
Purchase #7	$184.37	5.736%	$194.9455	$194.95	$194.95	$194.90
7 purchase totals =	$963.97		$1,035.0044	$1,035.01	$1,035.05	$1,034.90