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	$60.53	3.634%	$62.7297	$62.73	$62.75	$62.70
Purchase #2	$216.39	8.292%	$234.3331	$234.33	$234.35	$234.30
Purchase #3	$225.46	13.721%	$256.3954	$256.40	$256.40	$256.40
Purchase #4	$152.53	10.490%	$168.5304	$168.53	$168.55	$168.50
Purchase #5	$123.28	12.793%	$139.0512	$139.05	$139.05	$139.10
Purchase #6	$100.69	13.809%	$114.5943	$114.59	$114.60	$114.60
Purchase #7	$68.35	5.823%	$72.33	$72.33	$72.35	$72.30
7 purchase totals =	$947.23		$1,047.9641	$1,047.96	$1,048.05	$1,047.90