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	$153.80	11.650%	$171.7177	$171.72	$171.70	$171.70
Purchase #2	$156.69	3.473%	$162.1318	$162.13	$162.15	$162.10
Purchase #3	$234.77	11.725%	$262.2968	$262.30	$262.30	$262.30
Purchase #4	$5.57	13.680%	$6.332	$6.33	$6.35	$6.30
Purchase #5	$169.80	3.152%	$175.1521	$175.15	$175.15	$175.20
Purchase #6	$54.73	4.324%	$57.0965	$57.10	$57.10	$57.10
Purchase #7	$179.56	11.808%	$200.7624	$200.76	$200.75	$200.80
7 purchase totals =	$954.92		$1,035.4893	$1,035.49	$1,035.50	$1,035.50