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	$110.68	3.866%	$114.9589	$114.96	$114.95	$115.00
Purchase #2	$47.97	9.708%	$52.6269	$52.63	$52.65	$52.60
Purchase #3	$46.75	13.788%	$53.1959	$53.20	$53.20	$53.20
Purchase #4	$243.54	12.388%	$273.7097	$273.71	$273.70	$273.70
Purchase #5	$158.86	8.555%	$172.4505	$172.45	$172.45	$172.50
Purchase #6	$167.66	11.812%	$187.464	$187.46	$187.45	$187.50
Purchase #7	$160.78	7.322%	$172.5523	$172.55	$172.55	$172.60
7 purchase totals =	$936.24		$1,026.9582	$1,026.96	$1,026.95	$1,027.10