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	$13.33	6.249%	$14.163	$14.16	$14.15	$14.20
Purchase #2	$133.34	9.574%	$146.106	$146.11	$146.10	$146.10
Purchase #3	$175.34	6.687%	$187.065	$187.07	$187.05	$187.10
Purchase #4	$129.37	13.114%	$146.3356	$146.34	$146.35	$146.30
Purchase #5	$216.45	9.229%	$236.4262	$236.43	$236.45	$236.40
Purchase #6	$174.70	7.762%	$188.2602	$188.26	$188.25	$188.30
Purchase #7	$96.68	4.381%	$100.9156	$100.92	$100.90	$100.90
7 purchase totals =	$939.21		$1,019.2716	$1,019.29	$1,019.25	$1,019.30