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	$198.71	10.194%	$218.9665	$218.97	$218.95	$219.00
Purchase #2	$27.68	3.652%	$28.6909	$28.69	$28.70	$28.70
Purchase #3	$35.96	13.612%	$40.8549	$40.85	$40.85	$40.90
Purchase #4	$137.73	8.136%	$148.9357	$148.94	$148.95	$148.90
Purchase #5	$235.55	7.825%	$253.9818	$253.98	$254.00	$254.00
Purchase #6	$130.85	8.492%	$141.9618	$141.96	$141.95	$142.00
Purchase #7	$238.58	6.233%	$253.4507	$253.45	$253.45	$253.50
7 purchase totals =	$1,005.06		$1,086.8423	$1,086.84	$1,086.85	$1,087.00