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	$147.51	3.296%	$152.3719	$152.37	$152.35	$152.40
Purchase #2	$134.74	5.417%	$142.0389	$142.04	$142.05	$142.00
Purchase #3	$96.53	9.380%	$105.5845	$105.58	$105.60	$105.60
Purchase #4	$140.75	5.502%	$148.4941	$148.49	$148.50	$148.50
Purchase #5	$136.92	3.467%	$141.667	$141.67	$141.65	$141.70
Purchase #6	$62.91	3.213%	$64.9313	$64.93	$64.95	$64.90
Purchase #7	$47.85	9.291%	$52.2957	$52.30	$52.30	$52.30
7 purchase totals =	$767.21		$807.3834	$807.38	$807.40	$807.40