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	$172.90	13.824%	$196.8017	$196.80	$196.80	$196.80
Purchase #2	$64.68	11.780%	$72.2993	$72.30	$72.30	$72.30
Purchase #3	$160.48	10.579%	$177.4572	$177.46	$177.45	$177.50
Purchase #4	$67.84	8.119%	$73.3479	$73.35	$73.35	$73.30
Purchase #5	$178.88	3.557%	$185.2428	$185.24	$185.25	$185.20
Purchase #6	$168.95	6.456%	$179.8574	$179.86	$179.85	$179.90
Purchase #7	$133.29	5.612%	$140.7702	$140.77	$140.75	$140.80
7 purchase totals =	$947.02		$1,025.7765	$1,025.78	$1,025.75	$1,025.80