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	$197.55	8.860%	$215.0529	$215.05	$215.05	$215.10
Purchase #2	$210.32	13.837%	$239.422	$239.42	$239.40	$239.40
Purchase #3	$169.79	3.223%	$175.2623	$175.26	$175.25	$175.30
Purchase #4	$40.46	5.336%	$42.6189	$42.62	$42.60	$42.60
Purchase #5	$143.37	12.705%	$161.5852	$161.59	$161.60	$161.60
Purchase #6	$154.51	6.317%	$164.2704	$164.27	$164.25	$164.30
Purchase #7	$81.93	12.592%	$92.2466	$92.25	$92.25	$92.20
7 purchase totals =	$997.93		$1,090.4583	$1,090.46	$1,090.40	$1,090.50