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	$61.33	4.158%	$63.8801	$63.88	$63.90	$63.90
Purchase #2	$6.74	6.600%	$7.1848	$7.18	$7.20	$7.20
Purchase #3	$34.69	6.356%	$36.8949	$36.89	$36.90	$36.90
Purchase #4	$243.33	6.254%	$258.5479	$258.55	$258.55	$258.50
Purchase #5	$220.94	13.789%	$251.4054	$251.41	$251.40	$251.40
Purchase #6	$183.75	12.296%	$206.3439	$206.34	$206.35	$206.30
Purchase #7	$176.89	11.104%	$196.5319	$196.53	$196.55	$196.50
7 purchase totals =	$927.67		$1,020.7889	$1,020.78	$1,020.85	$1,020.70