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	$190.37	3.404%	$196.8502	$196.85	$196.85	$196.90
Purchase #2	$111.59	7.851%	$120.3509	$120.35	$120.35	$120.40
Purchase #3	$62.66	7.598%	$67.4209	$67.42	$67.40	$67.40
Purchase #4	$21.68	7.588%	$23.3251	$23.33	$23.35	$23.30
Purchase #5	$53.42	12.117%	$59.8929	$59.89	$59.90	$59.90
Purchase #6	$228.32	12.708%	$257.3349	$257.33	$257.35	$257.30
Purchase #7	$43.88	10.164%	$48.34	$48.34	$48.35	$48.30
7 purchase totals =	$711.92		$773.5149	$773.51	$773.55	$773.50