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	$176.69	11.114%	$196.3273	$196.33	$196.35	$196.30
Purchase #2	$103.67	4.218%	$108.0428	$108.04	$108.05	$108.00
Purchase #3	$125.37	13.579%	$142.394	$142.39	$142.40	$142.40
Purchase #4	$143.77	4.338%	$150.0067	$150.01	$150.00	$150.00
Purchase #5	$66.97	10.316%	$73.8786	$73.88	$73.90	$73.90
Purchase #6	$198.92	9.311%	$217.4414	$217.44	$217.45	$217.40
Purchase #7	$221.62	3.597%	$229.5917	$229.59	$229.60	$229.60
7 purchase totals =	$1,037.01		$1,117.6825	$1,117.68	$1,117.75	$1,117.60