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	$60.63	3.447%	$62.7199	$62.72	$62.70	$62.70
Purchase #2	$194.42	8.817%	$211.562	$211.56	$211.55	$211.60
Purchase #3	$176.42	7.807%	$190.1931	$190.19	$190.20	$190.20
Purchase #4	$235.76	10.850%	$261.34	$261.34	$261.35	$261.30
Purchase #5	$62.32	7.283%	$66.8588	$66.86	$66.85	$66.90
Purchase #6	$95.37	5.160%	$100.2911	$100.29	$100.30	$100.30
Purchase #7	$136.45	5.727%	$144.2645	$144.26	$144.25	$144.30
7 purchase totals =	$961.37		$1,037.2294	$1,037.22	$1,037.20	$1,037.30