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	$43.89	9.268%	$47.9577	$47.96	$47.95	$48.00
Purchase #2	$34.49	6.747%	$36.817	$36.82	$36.80	$36.80
Purchase #3	$85.52	5.611%	$90.3185	$90.32	$90.30	$90.30
Purchase #4	$88.54	7.426%	$95.115	$95.12	$95.10	$95.10
Purchase #5	$88.43	12.624%	$99.5934	$99.59	$99.60	$99.60
Purchase #6	$145.60	3.556%	$150.7775	$150.78	$150.80	$150.80
Purchase #7	$170.49	6.666%	$181.8549	$181.85	$181.85	$181.90
7 purchase totals =	$656.96		$702.4340	$702.44	$702.40	$702.50