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	$178.84	7.278%	$191.856	$191.86	$191.85	$191.90
Purchase #2	$184.59	4.868%	$193.5758	$193.58	$193.60	$193.60
Purchase #3	$35.72	7.599%	$38.4344	$38.43	$38.45	$38.40
Purchase #4	$163.48	13.356%	$185.3144	$185.31	$185.30	$185.30
Purchase #5	$5.89	10.576%	$6.5129	$6.51	$6.50	$6.50
Purchase #6	$246.54	9.119%	$269.022	$269.02	$269.00	$269.00
Purchase #7	$137.48	10.726%	$152.2261	$152.23	$152.25	$152.20
7 purchase totals =	$952.54		$1,036.9416	$1,036.94	$1,036.95	$1,036.90