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	$79.55	9.364%	$86.9991	$87.00	$87.00	$87.00
Purchase #2	$196.67	4.504%	$205.528	$205.53	$205.55	$205.50
Purchase #3	$131.53	8.376%	$142.547	$142.55	$142.55	$142.50
Purchase #4	$245.44	13.458%	$278.4713	$278.47	$278.45	$278.50
Purchase #5	$215.74	6.137%	$228.98	$228.98	$229.00	$229.00
Purchase #6	$238.88	11.107%	$265.4124	$265.41	$265.40	$265.40
Purchase #7	$188.72	4.103%	$196.4632	$196.46	$196.45	$196.50
7 purchase totals =	$1,296.53		$1,404.4010	$1,404.40	$1,404.40	$1,404.40