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	$162.30	7.607%	$174.6462	$174.65	$174.65	$174.60
Purchase #2	$149.76	12.631%	$168.6762	$168.68	$168.70	$168.70
Purchase #3	$72.45	6.780%	$77.3621	$77.36	$77.35	$77.40
Purchase #4	$140.53	8.835%	$152.9458	$152.95	$152.95	$152.90
Purchase #5	$238.38	13.147%	$269.7198	$269.72	$269.70	$269.70
Purchase #6	$83.89	10.628%	$92.8058	$92.81	$92.80	$92.80
Purchase #7	$86.36	3.140%	$89.0717	$89.07	$89.05	$89.10
7 purchase totals =	$933.67		$1,025.2276	$1,025.24	$1,025.20	$1,025.20