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	$64.57	7.409%	$69.354	$69.35	$69.35	$69.40
Purchase #2	$32.42	9.553%	$35.5171	$35.52	$35.50	$35.50
Purchase #3	$12.55	10.414%	$13.857	$13.86	$13.85	$13.90
Purchase #4	$39.66	9.572%	$43.4563	$43.46	$43.45	$43.50
Purchase #5	$110.32	9.707%	$121.0288	$121.03	$121.05	$121.00
Purchase #6	$180.66	8.578%	$196.157	$196.16	$196.15	$196.20
Purchase #7	$13.46	12.500%	$15.1425	$15.14	$15.15	$15.10
7 purchase totals =	$453.64		$494.5127	$494.52	$494.50	$494.60