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	$93.86	10.142%	$103.3793	$103.38	$103.40	$103.40
Purchase #2	$164.28	6.691%	$175.272	$175.27	$175.25	$175.30
Purchase #3	$237.95	13.375%	$269.7758	$269.78	$269.80	$269.80
Purchase #4	$152.57	10.617%	$168.7684	$168.77	$168.75	$168.80
Purchase #5	$29.38	10.648%	$32.5084	$32.51	$32.50	$32.50
Purchase #6	$197.34	13.861%	$224.6933	$224.69	$224.70	$224.70
Purchase #7	$47.52	4.170%	$49.5016	$49.50	$49.50	$49.50
7 purchase totals =	$922.90		$1,023.8988	$1,023.90	$1,023.90	$1,024.00