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	$220.30	8.343%	$238.6796	$238.68	$238.70	$238.70
Purchase #2	$12.93	5.464%	$13.6365	$13.64	$13.65	$13.60
Purchase #3	$106.71	4.454%	$111.4629	$111.46	$111.45	$111.50
Purchase #4	$27.48	3.674%	$28.4896	$28.49	$28.50	$28.50
Purchase #5	$250.60	7.255%	$268.781	$268.78	$268.80	$268.80
Purchase #6	$242.94	3.369%	$251.1246	$251.12	$251.10	$251.10
Purchase #7	$118.93	4.546%	$124.3366	$124.34	$124.35	$124.30
7 purchase totals =	$979.89		$1,036.5108	$1,036.51	$1,036.55	$1,036.50