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	$215.65	8.298%	$233.5446	$233.54	$233.55	$233.50
Purchase #2	$20.66	10.635%	$22.8572	$22.86	$22.85	$22.90
Purchase #3	$185.69	5.825%	$196.5064	$196.51	$196.50	$196.50
Purchase #4	$226.91	3.466%	$234.7747	$234.77	$234.75	$234.80
Purchase #5	$81.95	13.866%	$93.3132	$93.31	$93.30	$93.30
Purchase #6	$196.94	12.354%	$221.27	$221.27	$221.25	$221.30
Purchase #7	$199.53	7.426%	$214.3471	$214.35	$214.35	$214.30
7 purchase totals =	$1,127.33		$1,216.6132	$1,216.61	$1,216.55	$1,216.60