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	$57.49	6.382%	$61.159	$61.16	$61.15	$61.20
Purchase #2	$190.29	3.512%	$196.973	$196.97	$196.95	$197.00
Purchase #3	$242.41	8.435%	$262.8573	$262.86	$262.85	$262.90
Purchase #4	$35.95	4.216%	$37.4657	$37.47	$37.45	$37.50
Purchase #5	$173.85	6.838%	$185.7379	$185.74	$185.75	$185.70
Purchase #6	$177.60	7.200%	$190.3872	$190.39	$190.40	$190.40
Purchase #7	$230.98	9.109%	$252.02	$252.02	$252.00	$252.00
7 purchase totals =	$1,108.57		$1,186.6001	$1,186.61	$1,186.55	$1,186.70