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	$187.72	4.704%	$196.5503	$196.55	$196.55	$196.60
Purchase #2	$11.68	10.508%	$12.9073	$12.91	$12.90	$12.90
Purchase #3	$235.27	7.757%	$253.5199	$253.52	$253.50	$253.50
Purchase #4	$213.29	13.448%	$241.9732	$241.97	$241.95	$242.00
Purchase #5	$142.34	3.593%	$147.4543	$147.45	$147.45	$147.50
Purchase #6	$42.90	7.316%	$46.0386	$46.04	$46.05	$46.00
Purchase #7	$142.65	4.217%	$148.6656	$148.67	$148.65	$148.70
7 purchase totals =	$975.85		$1,047.1092	$1,047.11	$1,047.05	$1,047.20