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	$89.61	3.710%	$92.9345	$92.93	$92.95	$92.90
Purchase #2	$190.30	10.144%	$209.604	$209.60	$209.60	$209.60
Purchase #3	$186.53	3.307%	$192.6985	$192.70	$192.70	$192.70
Purchase #4	$28.40	3.765%	$29.4693	$29.47	$29.45	$29.50
Purchase #5	$64.56	7.709%	$69.5369	$69.54	$69.55	$69.50
Purchase #6	$143.32	12.609%	$161.3912	$161.39	$161.40	$161.40
Purchase #7	$232.67	13.586%	$264.2805	$264.28	$264.30	$264.30
7 purchase totals =	$935.39		$1,019.9149	$1,019.91	$1,019.95	$1,019.90