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	$201.58	6.704%	$215.0939	$215.09	$215.10	$215.10
Purchase #2	$114.79	13.214%	$129.9584	$129.96	$129.95	$130.00
Purchase #3	$14.82	6.491%	$15.782	$15.78	$15.80	$15.80
Purchase #4	$145.25	4.871%	$152.3251	$152.33	$152.35	$152.30
Purchase #5	$41.53	11.130%	$46.1523	$46.15	$46.15	$46.20
Purchase #6	$56.94	7.771%	$61.3648	$61.36	$61.35	$61.40
Purchase #7	$101.91	3.568%	$105.5461	$105.55	$105.55	$105.50
7 purchase totals =	$676.82		$726.2226	$726.22	$726.25	$726.30