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	$188.38	4.253%	$196.3918	$196.39	$196.40	$196.40
Purchase #2	$33.35	3.585%	$34.5456	$34.55	$34.55	$34.50
Purchase #3	$50.38	5.349%	$53.0748	$53.07	$53.05	$53.10
Purchase #4	$155.26	10.515%	$171.5856	$171.59	$171.60	$171.60
Purchase #5	$87.66	13.819%	$99.7737	$99.77	$99.75	$99.80
Purchase #6	$178.25	13.586%	$202.467	$202.47	$202.45	$202.50
Purchase #7	$6.59	11.873%	$7.3724	$7.37	$7.35	$7.40
7 purchase totals =	$699.87		$765.2109	$765.21	$765.15	$765.30