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	$119.66	5.361%	$126.075	$126.08	$126.10	$126.10
Purchase #2	$225.34	12.546%	$253.6112	$253.61	$253.60	$253.60
Purchase #3	$67.50	5.613%	$71.2888	$71.29	$71.30	$71.30
Purchase #4	$161.64	8.445%	$175.2905	$175.29	$175.30	$175.30
Purchase #5	$109.93	9.222%	$120.0677	$120.07	$120.05	$120.10
Purchase #6	$118.92	4.108%	$123.8052	$123.81	$123.80	$123.80
Purchase #7	$73.72	13.319%	$83.5388	$83.54	$83.55	$83.50
7 purchase totals =	$876.71		$953.6772	$953.69	$953.70	$953.70