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	$157.60	11.117%	$175.1204	$175.12	$175.10	$175.10
Purchase #2	$72.34	9.823%	$79.446	$79.45	$79.45	$79.40
Purchase #3	$163.61	12.620%	$184.2576	$184.26	$184.25	$184.30
Purchase #4	$236.84	6.139%	$251.3796	$251.38	$251.40	$251.40
Purchase #5	$78.68	4.794%	$82.4519	$82.45	$82.45	$82.50
Purchase #6	$139.42	3.391%	$144.1477	$144.15	$144.15	$144.10
Purchase #7	$126.87	12.358%	$142.5486	$142.55	$142.55	$142.50
7 purchase totals =	$975.36		$1,059.3518	$1,059.36	$1,059.35	$1,059.30