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	$82.97	13.748%	$94.3767	$94.38	$94.40	$94.40
Purchase #2	$240.26	13.604%	$272.945	$272.95	$272.95	$272.90
Purchase #3	$185.81	6.257%	$197.4361	$197.44	$197.45	$197.40
Purchase #4	$103.86	4.474%	$108.5067	$108.51	$108.50	$108.50
Purchase #5	$168.62	7.629%	$181.484	$181.48	$181.50	$181.50
Purchase #6	$216.30	12.215%	$242.721	$242.72	$242.70	$242.70
Purchase #7	$102.99	8.103%	$111.3353	$111.34	$111.35	$111.30
7 purchase totals =	$1,100.81		$1,208.8048	$1,208.82	$1,208.85	$1,208.70