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	$85.57	9.190%	$93.4339	$93.43	$93.45	$93.40
Purchase #2	$241.78	6.624%	$257.7955	$257.80	$257.80	$257.80
Purchase #3	$142.64	11.569%	$159.142	$159.14	$159.15	$159.10
Purchase #4	$162.60	3.608%	$168.4666	$168.47	$168.45	$168.50
Purchase #5	$35.87	3.614%	$37.1663	$37.17	$37.15	$37.20
Purchase #6	$213.46	4.718%	$223.531	$223.53	$223.55	$223.50
Purchase #7	$196.33	6.402%	$208.899	$208.90	$208.90	$208.90
7 purchase totals =	$1,078.25		$1,148.4343	$1,148.44	$1,148.45	$1,148.40