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	$106.89	4.793%	$112.0132	$112.01	$112.00	$112.00
Purchase #2	$42.79	13.657%	$48.6338	$48.63	$48.65	$48.60
Purchase #3	$176.36	4.163%	$183.7019	$183.70	$183.70	$183.70
Purchase #4	$136.33	10.425%	$150.5424	$150.54	$150.55	$150.50
Purchase #5	$158.77	3.359%	$164.1031	$164.10	$164.10	$164.10
Purchase #6	$151.94	11.300%	$169.1092	$169.11	$169.10	$169.10
Purchase #7	$134.46	3.824%	$139.6018	$139.60	$139.60	$139.60
7 purchase totals =	$907.54		$967.7054	$967.69	$967.70	$967.60