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	$199.29	6.511%	$212.2658	$212.27	$212.25	$212.30
Purchase #2	$17.72	4.321%	$18.4857	$18.49	$18.50	$18.50
Purchase #3	$33.68	3.663%	$34.9137	$34.91	$34.90	$34.90
Purchase #4	$71.50	13.202%	$80.9394	$80.94	$80.95	$80.90
Purchase #5	$130.42	9.109%	$142.3	$142.30	$142.30	$142.30
Purchase #6	$229.27	13.555%	$260.3475	$260.35	$260.35	$260.30
Purchase #7	$82.74	3.244%	$85.4241	$85.42	$85.40	$85.40
7 purchase totals =	$764.62		$834.6762	$834.68	$834.65	$834.60