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	$218.79	3.192%	$225.7738	$225.77	$225.75	$225.80
Purchase #2	$157.89	10.143%	$173.9048	$173.90	$173.90	$173.90
Purchase #3	$85.27	8.572%	$92.5793	$92.58	$92.60	$92.60
Purchase #4	$212.81	7.391%	$228.5388	$228.54	$228.55	$228.50
Purchase #5	$25.82	11.460%	$28.779	$28.78	$28.80	$28.80
Purchase #6	$225.68	5.730%	$238.6115	$238.61	$238.60	$238.60
Purchase #7	$20.47	9.802%	$22.4765	$22.48	$22.50	$22.50
7 purchase totals =	$946.73		$1,010.6637	$1,010.66	$1,010.70	$1,010.70