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	$58.41	10.871%	$64.7598	$64.76	$64.75	$64.80
Purchase #2	$220.55	3.638%	$228.5736	$228.57	$228.55	$228.60
Purchase #3	$242.88	5.721%	$256.7752	$256.78	$256.80	$256.80
Purchase #4	$76.36	12.834%	$86.16	$86.16	$86.15	$86.20
Purchase #5	$184.94	6.434%	$196.839	$196.84	$196.85	$196.80
Purchase #6	$31.30	3.571%	$32.4177	$32.42	$32.40	$32.40
Purchase #7	$139.41	5.285%	$146.7778	$146.78	$146.80	$146.80
7 purchase totals =	$953.85		$1,012.3031	$1,012.31	$1,012.30	$1,012.40