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	$233.98	4.392%	$244.2564	$244.26	$244.25	$244.30
Purchase #2	$21.77	8.807%	$23.6873	$23.69	$23.70	$23.70
Purchase #3	$61.61	9.207%	$67.2824	$67.28	$67.30	$67.30
Purchase #4	$90.33	11.124%	$100.3783	$100.38	$100.40	$100.40
Purchase #5	$143.71	6.563%	$153.1417	$153.14	$153.15	$153.10
Purchase #6	$85.81	9.618%	$94.0632	$94.06	$94.05	$94.10
Purchase #7	$249.94	3.481%	$258.6404	$258.64	$258.65	$258.60
7 purchase totals =	$887.15		$941.4497	$941.45	$941.50	$941.50