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	$58.89	4.506%	$61.5436	$61.54	$61.55	$61.50
Purchase #2	$12.52	9.821%	$13.7496	$13.75	$13.75	$13.70
Purchase #3	$53.57	8.738%	$58.2509	$58.25	$58.25	$58.30
Purchase #4	$25.40	12.684%	$28.6217	$28.62	$28.60	$28.60
Purchase #5	$82.66	6.838%	$88.3123	$88.31	$88.30	$88.30
Purchase #6	$24.40	3.611%	$25.2811	$25.28	$25.30	$25.30
Purchase #7	$177.42	5.259%	$186.7505	$186.75	$186.75	$186.80
7 purchase totals =	$434.86		$462.5097	$462.50	$462.50	$462.50