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	$200.53	8.631%	$217.8377	$217.84	$217.85	$217.80
Purchase #2	$82.57	9.637%	$90.5273	$90.53	$90.55	$90.50
Purchase #3	$29.66	12.760%	$33.4446	$33.44	$33.45	$33.40
Purchase #4	$237.77	3.419%	$245.8994	$245.90	$245.90	$245.90
Purchase #5	$156.90	3.390%	$162.2189	$162.22	$162.20	$162.20
Purchase #6	$211.45	4.776%	$221.5489	$221.55	$221.55	$221.50
Purchase #7	$187.55	4.729%	$196.4192	$196.42	$196.40	$196.40
7 purchase totals =	$1,106.43		$1,167.8960	$1,167.90	$1,167.90	$1,167.70