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	$203.27	13.457%	$230.624	$230.62	$230.60	$230.60
Purchase #2	$118.87	5.150%	$124.9918	$124.99	$125.00	$125.00
Purchase #3	$137.54	9.718%	$150.9061	$150.91	$150.90	$150.90
Purchase #4	$149.89	12.404%	$168.4824	$168.48	$168.50	$168.50
Purchase #5	$125.94	3.635%	$130.5179	$130.52	$130.50	$130.50
Purchase #6	$145.81	12.222%	$163.6309	$163.63	$163.65	$163.60
Purchase #7	$180.31	9.135%	$196.7813	$196.78	$196.80	$196.80
7 purchase totals =	$1,061.63		$1,165.9344	$1,165.93	$1,165.95	$1,165.90