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	$87.71	7.609%	$94.3839	$94.38	$94.40	$94.40
Purchase #2	$215.52	8.356%	$233.5289	$233.53	$233.55	$233.50
Purchase #3	$225.79	6.564%	$240.6109	$240.61	$240.60	$240.60
Purchase #4	$88.72	12.219%	$99.5607	$99.56	$99.55	$99.60
Purchase #5	$77.76	5.610%	$82.1223	$82.12	$82.10	$82.10
Purchase #6	$210.48	7.434%	$226.1271	$226.13	$226.15	$226.10
Purchase #7	$212.44	9.149%	$231.8761	$231.88	$231.90	$231.90
7 purchase totals =	$1,118.42		$1,208.2099	$1,208.21	$1,208.25	$1,208.20