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	$61.90	9.743%	$67.9309	$67.93	$67.95	$67.90
Purchase #2	$115.58	12.149%	$129.6218	$129.62	$129.60	$129.60
Purchase #3	$91.30	12.200%	$102.4386	$102.44	$102.45	$102.40
Purchase #4	$224.88	8.729%	$244.5098	$244.51	$244.50	$244.50
Purchase #5	$140.93	4.418%	$147.1563	$147.16	$147.15	$147.20
Purchase #6	$208.35	4.638%	$218.0133	$218.01	$218.00	$218.00
Purchase #7	$97.45	12.807%	$109.9304	$109.93	$109.95	$109.90
7 purchase totals =	$940.39		$1,019.6011	$1,019.60	$1,019.60	$1,019.50