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	$80.79	3.402%	$83.5385	$83.54	$83.55	$83.50
Purchase #2	$70.73	4.464%	$73.8874	$73.89	$73.90	$73.90
Purchase #3	$166.61	4.870%	$174.7239	$174.72	$174.70	$174.70
Purchase #4	$139.51	10.754%	$154.5129	$154.51	$154.50	$154.50
Purchase #5	$238.46	3.359%	$246.4699	$246.47	$246.45	$246.50
Purchase #6	$232.27	10.269%	$256.1218	$256.12	$256.10	$256.10
Purchase #7	$150.86	8.358%	$163.4689	$163.47	$163.45	$163.50
7 purchase totals =	$1,079.23		$1,152.7233	$1,152.72	$1,152.65	$1,152.70