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	$89.88	3.737%	$93.2388	$93.24	$93.25	$93.20
Purchase #2	$42.91	11.589%	$47.8828	$47.88	$47.90	$47.90
Purchase #3	$44.38	3.452%	$45.912	$45.91	$45.90	$45.90
Purchase #4	$112.78	9.563%	$123.5652	$123.57	$123.55	$123.60
Purchase #5	$143.52	3.560%	$148.6293	$148.63	$148.65	$148.60
Purchase #6	$206.76	4.698%	$216.4736	$216.47	$216.45	$216.50
Purchase #7	$53.75	10.486%	$59.3862	$59.39	$59.40	$59.40
7 purchase totals =	$693.98		$735.0879	$735.09	$735.10	$735.10