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	$59.69	3.449%	$61.7487	$61.75	$61.75	$61.70
Purchase #2	$115.35	7.369%	$123.8501	$123.85	$123.85	$123.90
Purchase #3	$44.80	12.605%	$50.447	$50.45	$50.45	$50.40
Purchase #4	$60.88	8.662%	$66.1534	$66.15	$66.15	$66.20
Purchase #5	$224.27	11.515%	$250.0947	$250.09	$250.10	$250.10
Purchase #6	$33.73	3.415%	$34.8819	$34.88	$34.90	$34.90
Purchase #7	$243.60	10.377%	$268.8784	$268.88	$268.90	$268.90
7 purchase totals =	$782.32		$856.0542	$856.05	$856.10	$856.10