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	$182.98	7.510%	$196.7218	$196.72	$196.70	$196.70
Purchase #2	$57.76	13.159%	$65.3606	$65.36	$65.35	$65.40
Purchase #3	$209.61	13.208%	$237.2953	$237.30	$237.30	$237.30
Purchase #4	$162.51	3.708%	$168.5359	$168.54	$168.55	$168.50
Purchase #5	$5.50	10.599%	$6.0829	$6.08	$6.10	$6.10
Purchase #6	$146.96	9.195%	$160.473	$160.47	$160.45	$160.50
Purchase #7	$194.37	7.293%	$208.5454	$208.55	$208.55	$208.50
7 purchase totals =	$959.69		$1,043.0149	$1,043.02	$1,043.00	$1,043.00