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	$197.68	5.662%	$208.8726	$208.87	$208.85	$208.90
Purchase #2	$107.50	10.259%	$118.5284	$118.53	$118.55	$118.50
Purchase #3	$82.62	8.759%	$89.8567	$89.86	$89.85	$89.90
Purchase #4	$124.50	9.655%	$136.5205	$136.52	$136.50	$136.50
Purchase #5	$192.54	6.523%	$205.0994	$205.10	$205.10	$205.10
Purchase #6	$232.75	9.269%	$254.3236	$254.32	$254.30	$254.30
Purchase #7	$96.75	3.256%	$99.9002	$99.90	$99.90	$99.90
7 purchase totals =	$1,034.34		$1,113.1014	$1,113.10	$1,113.05	$1,113.10