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	$104.94	11.346%	$116.8465	$116.85	$116.85	$116.80
Purchase #2	$138.25	6.611%	$147.3897	$147.39	$147.40	$147.40
Purchase #3	$194.28	11.424%	$216.4745	$216.47	$216.45	$216.50
Purchase #4	$35.45	5.865%	$37.5291	$37.53	$37.55	$37.50
Purchase #5	$188.70	4.123%	$196.4801	$196.48	$196.50	$196.50
Purchase #6	$20.99	8.493%	$22.7727	$22.77	$22.75	$22.80
Purchase #7	$13.51	4.151%	$14.0708	$14.07	$14.05	$14.10
7 purchase totals =	$696.12		$751.5634	$751.56	$751.55	$751.60