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	$246.47	3.342%	$254.707	$254.71	$254.70	$254.70
Purchase #2	$43.79	5.443%	$46.1735	$46.17	$46.15	$46.20
Purchase #3	$48.39	8.861%	$52.6778	$52.68	$52.70	$52.70
Purchase #4	$240.48	12.799%	$271.259	$271.26	$271.25	$271.30
Purchase #5	$160.79	6.666%	$171.5083	$171.51	$171.50	$171.50
Purchase #6	$168.28	6.303%	$178.8867	$178.89	$178.90	$178.90
Purchase #7	$60.39	3.107%	$62.2663	$62.27	$62.25	$62.30
7 purchase totals =	$968.59		$1,037.4786	$1,037.49	$1,037.45	$1,037.60