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	$91.64	10.267%	$101.0487	$101.05	$101.05	$101.00
Purchase #2	$34.93	11.842%	$39.0664	$39.07	$39.05	$39.10
Purchase #3	$59.99	11.842%	$67.094	$67.09	$67.10	$67.10
Purchase #4	$28.53	4.731%	$29.8798	$29.88	$29.90	$29.90
Purchase #5	$48.33	10.842%	$53.5699	$53.57	$53.55	$53.60
Purchase #6	$140.51	8.186%	$152.0121	$152.01	$152.00	$152.00
Purchase #7	$73.39	11.487%	$81.8203	$81.82	$81.80	$81.80
7 purchase totals =	$477.32		$524.4912	$524.49	$524.45	$524.50