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	$56.69	8.516%	$61.5177	$61.52	$61.50	$61.50
Purchase #2	$143.41	7.393%	$154.0123	$154.01	$154.00	$154.00
Purchase #3	$84.69	6.153%	$89.901	$89.90	$89.90	$89.90
Purchase #4	$198.33	9.292%	$216.7588	$216.76	$216.75	$216.80
Purchase #5	$194.51	11.143%	$216.1842	$216.18	$216.20	$216.20
Purchase #6	$210.36	10.376%	$232.187	$232.19	$232.20	$232.20
Purchase #7	$180.83	5.302%	$190.4176	$190.42	$190.40	$190.40
7 purchase totals =	$1,068.82		$1,160.9786	$1,160.98	$1,160.95	$1,161.00