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	$105.56	8.454%	$114.484	$114.48	$114.50	$114.50
Purchase #2	$56.95	5.738%	$60.2178	$60.22	$60.20	$60.20
Purchase #3	$118.92	4.381%	$124.1299	$124.13	$124.15	$124.10
Purchase #4	$80.95	5.393%	$85.3156	$85.32	$85.30	$85.30
Purchase #5	$51.27	6.397%	$54.5497	$54.55	$54.55	$54.50
Purchase #6	$7.56	4.614%	$7.9088	$7.91	$7.90	$7.90
Purchase #7	$5.65	5.854%	$5.9808	$5.98	$6.00	$6.00
7 purchase totals =	$426.86		$452.5866	$452.59	$452.60	$452.50