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	$127.35	11.593%	$142.1137	$142.11	$142.10	$142.10
Purchase #2	$33.36	11.223%	$37.104	$37.10	$37.10	$37.10
Purchase #3	$105.73	11.413%	$117.797	$117.80	$117.80	$117.80
Purchase #4	$78.52	3.599%	$81.3459	$81.35	$81.35	$81.30
Purchase #5	$169.57	10.536%	$187.4359	$187.44	$187.45	$187.40
Purchase #6	$241.52	13.382%	$273.8402	$273.84	$273.85	$273.80
Purchase #7	$200.88	11.377%	$223.7341	$223.73	$223.75	$223.70
7 purchase totals =	$956.93		$1,063.3708	$1,063.37	$1,063.40	$1,063.20