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	$223.99	5.761%	$236.8941	$236.89	$236.90	$236.90
Purchase #2	$36.52	5.159%	$38.4041	$38.40	$38.40	$38.40
Purchase #3	$68.76	6.280%	$73.0781	$73.08	$73.10	$73.10
Purchase #4	$168.83	12.785%	$190.4149	$190.41	$190.40	$190.40
Purchase #5	$241.26	13.309%	$273.3693	$273.37	$273.35	$273.40
Purchase #6	$144.75	3.265%	$149.4761	$149.48	$149.50	$149.50
Purchase #7	$78.32	6.271%	$83.2314	$83.23	$83.25	$83.20
7 purchase totals =	$962.43		$1,044.8680	$1,044.86	$1,044.90	$1,044.90