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	$93.82	8.526%	$101.8191	$101.82	$101.80	$101.80
Purchase #2	$115.35	7.454%	$123.9482	$123.95	$123.95	$123.90
Purchase #3	$48.28	5.411%	$50.8924	$50.89	$50.90	$50.90
Purchase #4	$89.38	7.137%	$95.7591	$95.76	$95.75	$95.80
Purchase #5	$199.32	5.801%	$210.8826	$210.88	$210.90	$210.90
Purchase #6	$100.96	11.532%	$112.6027	$112.60	$112.60	$112.60
Purchase #7	$37.68	9.726%	$41.3448	$41.34	$41.35	$41.30
7 purchase totals =	$684.79		$737.2489	$737.24	$737.25	$737.20