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	$13.74	8.742%	$14.9412	$14.94	$14.95	$14.90
Purchase #2	$188.92	8.214%	$204.4379	$204.44	$204.45	$204.40
Purchase #3	$222.91	12.462%	$250.689	$250.69	$250.70	$250.70
Purchase #4	$176.87	4.678%	$185.144	$185.14	$185.15	$185.10
Purchase #5	$125.68	11.543%	$140.1872	$140.19	$140.20	$140.20
Purchase #6	$64.94	11.696%	$72.5354	$72.54	$72.55	$72.50
Purchase #7	$223.25	9.326%	$244.0703	$244.07	$244.05	$244.10
7 purchase totals =	$1,016.31		$1,112.0050	$1,112.01	$1,112.05	$1,111.90