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	$128.74	10.406%	$142.1367	$142.14	$142.15	$142.10
Purchase #2	$48.45	12.251%	$54.3856	$54.39	$54.40	$54.40
Purchase #3	$50.48	3.169%	$52.0797	$52.08	$52.10	$52.10
Purchase #4	$231.41	12.684%	$260.762	$260.76	$260.75	$260.80
Purchase #5	$113.77	10.632%	$125.866	$125.87	$125.85	$125.90
Purchase #6	$200.80	7.834%	$216.5307	$216.53	$216.55	$216.50
Purchase #7	$244.34	6.284%	$259.6943	$259.69	$259.70	$259.70
7 purchase totals =	$1,017.99		$1,111.4550	$1,111.46	$1,111.50	$1,111.50