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	$100.69	4.611%	$105.3328	$105.33	$105.35	$105.30
Purchase #2	$217.34	10.465%	$240.0846	$240.08	$240.10	$240.10
Purchase #3	$130.25	3.374%	$134.6446	$134.64	$134.65	$134.60
Purchase #4	$170.90	13.126%	$193.3323	$193.33	$193.35	$193.30
Purchase #5	$100.57	4.324%	$104.9186	$104.92	$104.90	$104.90
Purchase #6	$176.52	11.468%	$196.7633	$196.76	$196.75	$196.80
Purchase #7	$139.38	8.347%	$151.014	$151.01	$151.00	$151.00
7 purchase totals =	$1,035.65		$1,126.0902	$1,126.07	$1,126.10	$1,126.00