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	$142.70	5.590%	$150.6769	$150.68	$150.70	$150.70
Purchase #2	$67.38	4.273%	$70.2591	$70.26	$70.25	$70.30
Purchase #3	$77.51	10.216%	$85.4284	$85.43	$85.45	$85.40
Purchase #4	$173.54	6.189%	$184.2804	$184.28	$184.30	$184.30
Purchase #5	$72.34	5.515%	$76.3296	$76.33	$76.35	$76.30
Purchase #6	$224.82	5.369%	$236.8906	$236.89	$236.90	$236.90
Purchase #7	$228.98	12.315%	$257.1789	$257.18	$257.20	$257.20
7 purchase totals =	$987.27		$1,061.0439	$1,061.05	$1,061.15	$1,061.10