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	$176.89	9.864%	$194.3384	$194.34	$194.35	$194.30
Purchase #2	$217.68	9.416%	$238.1767	$238.18	$238.20	$238.20
Purchase #3	$56.71	13.685%	$64.4708	$64.47	$64.45	$64.50
Purchase #4	$117.78	8.330%	$127.5911	$127.59	$127.60	$127.60
Purchase #5	$70.77	10.295%	$78.0558	$78.06	$78.05	$78.10
Purchase #6	$243.93	7.380%	$261.932	$261.93	$261.95	$261.90
Purchase #7	$152.56	10.235%	$168.1745	$168.17	$168.15	$168.20
7 purchase totals =	$1,036.32		$1,132.7393	$1,132.74	$1,132.75	$1,132.80