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	$118.58	9.647%	$130.0194	$130.02	$130.00	$130.00
Purchase #2	$37.61	12.744%	$42.403	$42.40	$42.40	$42.40
Purchase #3	$196.96	4.690%	$206.1974	$206.20	$206.20	$206.20
Purchase #4	$223.59	3.217%	$230.7829	$230.78	$230.80	$230.80
Purchase #5	$105.89	10.317%	$116.8147	$116.81	$116.80	$116.80
Purchase #6	$40.28	5.334%	$42.4285	$42.43	$42.45	$42.40
Purchase #7	$192.98	3.661%	$200.045	$200.05	$200.05	$200.00
7 purchase totals =	$915.89		$968.6909	$968.69	$968.70	$968.60