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	$186.67	7.529%	$200.7244	$200.72	$200.70	$200.70
Purchase #2	$61.78	9.233%	$67.4841	$67.48	$67.50	$67.50
Purchase #3	$85.29	3.845%	$88.5694	$88.57	$88.55	$88.60
Purchase #4	$189.86	10.368%	$209.5447	$209.54	$209.55	$209.50
Purchase #5	$166.51	5.633%	$175.8895	$175.89	$175.90	$175.90
Purchase #6	$179.25	3.109%	$184.8229	$184.82	$184.80	$184.80
Purchase #7	$31.32	12.517%	$35.2403	$35.24	$35.25	$35.20
7 purchase totals =	$900.68		$962.2753	$962.26	$962.25	$962.20