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	$64.44	10.391%	$71.136	$71.14	$71.15	$71.10
Purchase #2	$9.70	13.372%	$10.9971	$11.00	$11.00	$11.00
Purchase #3	$137.92	9.403%	$150.8886	$150.89	$150.90	$150.90
Purchase #4	$243.56	9.503%	$266.7055	$266.71	$266.70	$266.70
Purchase #5	$186.40	5.244%	$196.1748	$196.17	$196.15	$196.20
Purchase #6	$175.29	6.817%	$187.2395	$187.24	$187.25	$187.20
Purchase #7	$166.61	11.659%	$186.0351	$186.04	$186.05	$186.00
7 purchase totals =	$983.92		$1,069.1766	$1,069.19	$1,069.20	$1,069.10