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	$88.53	7.743%	$95.3849	$95.38	$95.40	$95.40
Purchase #2	$51.54	3.126%	$53.1511	$53.15	$53.15	$53.20
Purchase #3	$178.80	3.785%	$185.5676	$185.57	$185.55	$185.60
Purchase #4	$109.90	12.259%	$123.3726	$123.37	$123.35	$123.40
Purchase #5	$18.61	8.690%	$20.2272	$20.23	$20.25	$20.20
Purchase #6	$143.67	6.796%	$153.4338	$153.43	$153.45	$153.40
Purchase #7	$186.61	9.658%	$204.6328	$204.63	$204.65	$204.60
7 purchase totals =	$777.66		$835.7700	$835.76	$835.80	$835.80