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	$215.73	13.440%	$244.7241	$244.72	$244.70	$244.70
Purchase #2	$244.78	9.528%	$268.1026	$268.10	$268.10	$268.10
Purchase #3	$170.25	10.478%	$188.0888	$188.09	$188.10	$188.10
Purchase #4	$45.35	6.219%	$48.1703	$48.17	$48.15	$48.20
Purchase #5	$96.50	9.383%	$105.5546	$105.55	$105.55	$105.60
Purchase #6	$141.35	10.218%	$155.7931	$155.79	$155.80	$155.80
Purchase #7	$179.56	3.638%	$186.0924	$186.09	$186.10	$186.10
7 purchase totals =	$1,093.52		$1,196.5259	$1,196.51	$1,196.50	$1,196.60