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	$198.32	7.245%	$212.6883	$212.69	$212.70	$212.70
Purchase #2	$127.66	11.738%	$142.6447	$142.64	$142.65	$142.60
Purchase #3	$200.54	5.866%	$212.3037	$212.30	$212.30	$212.30
Purchase #4	$189.70	3.527%	$196.3907	$196.39	$196.40	$196.40
Purchase #5	$41.74	4.856%	$43.7669	$43.77	$43.75	$43.80
Purchase #6	$210.62	8.259%	$228.0151	$228.02	$228.00	$228.00
Purchase #7	$68.70	10.451%	$75.8798	$75.88	$75.90	$75.90
7 purchase totals =	$1,037.28		$1,111.6892	$1,111.69	$1,111.70	$1,111.70