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	$175.68	6.120%	$186.4316	$186.43	$186.45	$186.40
Purchase #2	$55.94	5.550%	$59.0447	$59.04	$59.05	$59.00
Purchase #3	$52.81	13.370%	$59.8707	$59.87	$59.85	$59.90
Purchase #4	$227.65	11.512%	$253.8571	$253.86	$253.85	$253.90
Purchase #5	$160.44	5.568%	$169.3733	$169.37	$169.35	$169.40
Purchase #6	$188.29	7.210%	$201.8657	$201.87	$201.85	$201.90
Purchase #7	$94.89	10.811%	$105.1486	$105.15	$105.15	$105.10
7 purchase totals =	$955.70		$1,035.5917	$1,035.59	$1,035.55	$1,035.60