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	$163.52	6.269%	$173.7711	$173.77	$173.75	$173.80
Purchase #2	$104.60	13.272%	$118.4825	$118.48	$118.50	$118.50
Purchase #3	$61.58	4.409%	$64.2951	$64.30	$64.30	$64.30
Purchase #4	$182.30	7.546%	$196.0564	$196.06	$196.05	$196.10
Purchase #5	$114.34	4.628%	$119.6317	$119.63	$119.65	$119.60
Purchase #6	$220.77	3.504%	$228.5058	$228.51	$228.50	$228.50
Purchase #7	$217.75	6.182%	$231.2113	$231.21	$231.20	$231.20
7 purchase totals =	$1,064.86		$1,131.9539	$1,131.96	$1,131.95	$1,132.00