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	$141.83	7.713%	$152.7693	$152.77	$152.75	$152.80
Purchase #2	$51.67	4.744%	$54.1212	$54.12	$54.10	$54.10
Purchase #3	$82.65	9.833%	$90.777	$90.78	$90.80	$90.80
Purchase #4	$63.75	7.563%	$68.5714	$68.57	$68.55	$68.60
Purchase #5	$7.68	8.136%	$8.3048	$8.30	$8.30	$8.30
Purchase #6	$156.52	6.252%	$166.3056	$166.31	$166.30	$166.30
Purchase #7	$179.77	3.111%	$185.3626	$185.36	$185.35	$185.40
7 purchase totals =	$683.87		$726.2119	$726.21	$726.15	$726.30