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	$239.32	10.267%	$263.891	$263.89	$263.90	$263.90
Purchase #2	$47.81	9.672%	$52.4342	$52.43	$52.45	$52.40
Purchase #3	$55.83	9.829%	$61.3175	$61.32	$61.30	$61.30
Purchase #4	$103.89	3.655%	$107.6872	$107.69	$107.70	$107.70
Purchase #5	$191.68	10.545%	$211.8927	$211.89	$211.90	$211.90
Purchase #6	$223.50	7.623%	$240.5374	$240.54	$240.55	$240.50
Purchase #7	$74.75	13.262%	$84.6633	$84.66	$84.65	$84.70
7 purchase totals =	$936.78		$1,022.4233	$1,022.42	$1,022.45	$1,022.40