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	$150.89	4.414%	$157.5503	$157.55	$157.55	$157.60
Purchase #2	$13.40	5.164%	$14.092	$14.09	$14.10	$14.10
Purchase #3	$33.25	8.649%	$36.1258	$36.13	$36.15	$36.10
Purchase #4	$85.47	6.306%	$90.8597	$90.86	$90.85	$90.90
Purchase #5	$100.52	4.157%	$104.6986	$104.70	$104.70	$104.70
Purchase #6	$89.33	6.220%	$94.8863	$94.89	$94.90	$94.90
Purchase #7	$219.93	3.781%	$228.2456	$228.25	$228.25	$228.20
7 purchase totals =	$692.79		$726.4583	$726.47	$726.50	$726.50