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	$196.38	13.592%	$223.072	$223.07	$223.05	$223.10
Purchase #2	$155.92	13.673%	$177.2389	$177.24	$177.25	$177.20
Purchase #3	$119.35	3.836%	$123.9283	$123.93	$123.95	$123.90
Purchase #4	$216.55	3.796%	$224.7702	$224.77	$224.75	$224.80
Purchase #5	$170.77	11.468%	$190.3539	$190.35	$190.35	$190.40
Purchase #6	$73.31	12.458%	$82.443	$82.44	$82.45	$82.40
Purchase #7	$98.45	5.209%	$103.5783	$103.58	$103.60	$103.60
7 purchase totals =	$1,030.73		$1,125.3846	$1,125.38	$1,125.40	$1,125.40