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	$196.43	10.838%	$217.7191	$217.72	$217.70	$217.70
Purchase #2	$97.56	8.596%	$105.9463	$105.95	$105.95	$105.90
Purchase #3	$29.49	10.580%	$32.61	$32.61	$32.60	$32.60
Purchase #4	$218.38	13.226%	$247.2629	$247.26	$247.25	$247.30
Purchase #5	$69.47	5.393%	$73.2165	$73.22	$73.20	$73.20
Purchase #6	$119.59	9.361%	$130.7848	$130.78	$130.80	$130.80
Purchase #7	$202.94	10.216%	$223.6724	$223.67	$223.65	$223.70
7 purchase totals =	$933.86		$1,031.2120	$1,031.21	$1,031.15	$1,031.20