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	$194.80	11.699%	$217.5897	$217.59	$217.60	$217.60
Purchase #2	$203.67	9.615%	$223.2529	$223.25	$223.25	$223.30
Purchase #3	$126.56	12.855%	$142.8293	$142.83	$142.85	$142.80
Purchase #4	$243.97	8.736%	$265.2832	$265.28	$265.30	$265.30
Purchase #5	$23.62	12.561%	$26.5869	$26.59	$26.60	$26.60
Purchase #6	$118.65	6.673%	$126.5675	$126.57	$126.55	$126.60
Purchase #7	$95.32	4.164%	$99.2891	$99.29	$99.30	$99.30
7 purchase totals =	$1,006.59		$1,101.3986	$1,101.40	$1,101.45	$1,101.50