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	$245.40	9.597%	$268.951	$268.95	$268.95	$269.00
Purchase #2	$165.51	3.349%	$171.0529	$171.05	$171.05	$171.10
Purchase #3	$218.78	10.516%	$241.7869	$241.79	$241.80	$241.80
Purchase #4	$121.87	8.801%	$132.5958	$132.60	$132.60	$132.60
Purchase #5	$90.96	9.387%	$99.4984	$99.50	$99.50	$99.50
Purchase #6	$77.61	6.847%	$82.924	$82.92	$82.90	$82.90
Purchase #7	$27.54	7.718%	$29.6655	$29.67	$29.65	$29.70
7 purchase totals =	$947.67		$1,026.4745	$1,026.48	$1,026.45	$1,026.60