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	$181.25	8.452%	$196.5693	$196.57	$196.55	$196.60
Purchase #2	$247.74	5.747%	$261.9776	$261.98	$262.00	$262.00
Purchase #3	$50.28	7.701%	$54.1521	$54.15	$54.15	$54.20
Purchase #4	$92.80	13.262%	$105.1071	$105.11	$105.10	$105.10
Purchase #5	$90.92	11.138%	$101.0467	$101.05	$101.05	$101.00
Purchase #6	$72.87	10.545%	$80.5541	$80.55	$80.55	$80.60
Purchase #7	$196.36	13.800%	$223.4577	$223.46	$223.45	$223.50
7 purchase totals =	$932.22		$1,022.8646	$1,022.87	$1,022.85	$1,023.00