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	$232.40	4.746%	$243.4297	$243.43	$243.45	$243.40
Purchase #2	$141.31	3.623%	$146.4297	$146.43	$146.45	$146.40
Purchase #3	$40.47	5.185%	$42.5684	$42.57	$42.55	$42.60
Purchase #4	$126.96	8.359%	$137.5726	$137.57	$137.55	$137.60
Purchase #5	$156.99	10.737%	$173.846	$173.85	$173.85	$173.80
Purchase #6	$63.69	4.267%	$66.4077	$66.41	$66.40	$66.40
Purchase #7	$209.32	6.205%	$222.3083	$222.31	$222.30	$222.30
7 purchase totals =	$971.14		$1,032.5624	$1,032.57	$1,032.55	$1,032.50