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	$228.33	7.457%	$245.3566	$245.36	$245.35	$245.40
Purchase #2	$50.40	5.334%	$53.0883	$53.09	$53.10	$53.10
Purchase #3	$143.95	6.230%	$152.9181	$152.92	$152.90	$152.90
Purchase #4	$77.44	11.243%	$86.1466	$86.15	$86.15	$86.10
Purchase #5	$174.29	12.767%	$196.5416	$196.54	$196.55	$196.50
Purchase #6	$214.32	5.744%	$226.6305	$226.63	$226.65	$226.60
Purchase #7	$115.48	5.183%	$121.4653	$121.47	$121.45	$121.50
7 purchase totals =	$1,004.21		$1,082.1470	$1,082.16	$1,082.15	$1,082.10