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	$146.58	11.164%	$162.9442	$162.94	$162.95	$162.90
Purchase #2	$103.50	11.727%	$115.6374	$115.64	$115.65	$115.60
Purchase #3	$175.97	4.193%	$183.3484	$183.35	$183.35	$183.30
Purchase #4	$137.30	4.818%	$143.9151	$143.92	$143.90	$143.90
Purchase #5	$155.88	11.675%	$174.079	$174.08	$174.10	$174.10
Purchase #6	$127.96	6.484%	$136.2569	$136.26	$136.25	$136.30
Purchase #7	$125.98	4.397%	$131.5193	$131.52	$131.50	$131.50
7 purchase totals =	$973.17		$1,047.7003	$1,047.71	$1,047.70	$1,047.60