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	$53.74	3.667%	$55.7106	$55.71	$55.70	$55.70
Purchase #2	$73.71	6.352%	$78.3921	$78.39	$78.40	$78.40
Purchase #3	$68.74	5.316%	$72.3942	$72.39	$72.40	$72.40
Purchase #4	$160.31	8.874%	$174.5359	$174.54	$174.55	$174.50
Purchase #5	$44.45	5.365%	$46.8347	$46.83	$46.85	$46.80
Purchase #6	$48.80	5.426%	$51.4479	$51.45	$51.45	$51.40
Purchase #7	$5.35	10.107%	$5.8907	$5.89	$5.90	$5.90
7 purchase totals =	$455.10		$485.2061	$485.20	$485.25	$485.10