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	$28.64	9.760%	$31.4353	$31.44	$31.45	$31.40
Purchase #2	$65.99	9.773%	$72.4392	$72.44	$72.45	$72.40
Purchase #3	$205.95	10.336%	$227.237	$227.24	$227.25	$227.20
Purchase #4	$103.47	7.387%	$111.1133	$111.11	$111.10	$111.10
Purchase #5	$201.83	5.338%	$212.6037	$212.60	$212.60	$212.60
Purchase #6	$152.80	9.398%	$167.1601	$167.16	$167.15	$167.20
Purchase #7	$225.65	6.686%	$240.737	$240.74	$240.75	$240.70
7 purchase totals =	$984.33		$1,062.7256	$1,062.73	$1,062.75	$1,062.60