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	$105.42	8.361%	$114.2342	$114.23	$114.25	$114.20
Purchase #2	$159.69	10.587%	$176.5964	$176.60	$176.60	$176.60
Purchase #3	$182.53	4.844%	$191.3718	$191.37	$191.35	$191.40
Purchase #4	$113.45	9.216%	$123.9056	$123.91	$123.90	$123.90
Purchase #5	$117.70	13.637%	$133.7507	$133.75	$133.75	$133.80
Purchase #6	$162.69	3.148%	$167.8115	$167.81	$167.80	$167.80
Purchase #7	$128.34	6.117%	$136.1906	$136.19	$136.20	$136.20
7 purchase totals =	$969.82		$1,043.8608	$1,043.86	$1,043.85	$1,043.90