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	$162.72	3.495%	$168.4071	$168.41	$168.40	$168.40
Purchase #2	$136.83	4.549%	$143.0544	$143.05	$143.05	$143.10
Purchase #3	$36.65	3.331%	$37.8708	$37.87	$37.85	$37.90
Purchase #4	$232.43	5.871%	$246.076	$246.08	$246.10	$246.10
Purchase #5	$228.81	10.803%	$253.5283	$253.53	$253.55	$253.50
Purchase #6	$208.73	3.560%	$216.1608	$216.16	$216.15	$216.20
Purchase #7	$37.53	3.677%	$38.91	$38.91	$38.90	$38.90
7 purchase totals =	$1,043.70		$1,104.0074	$1,104.01	$1,104.00	$1,104.10