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	$96.27	4.765%	$100.8573	$100.86	$100.85	$100.90
Purchase #2	$88.26	6.763%	$94.229	$94.23	$94.25	$94.20
Purchase #3	$210.89	12.169%	$236.5532	$236.55	$236.55	$236.60
Purchase #4	$24.65	12.102%	$27.6331	$27.63	$27.65	$27.60
Purchase #5	$187.61	12.761%	$211.5509	$211.55	$211.55	$211.60
Purchase #6	$119.34	11.611%	$133.1966	$133.20	$133.20	$133.20
Purchase #7	$229.46	13.235%	$259.829	$259.83	$259.85	$259.80
7 purchase totals =	$956.48		$1,063.8491	$1,063.85	$1,063.90	$1,063.90