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	$60.95	13.712%	$69.3075	$69.31	$69.30	$69.30
Purchase #2	$104.51	8.128%	$113.0046	$113.00	$113.00	$113.00
Purchase #3	$88.61	13.202%	$100.3083	$100.31	$100.30	$100.30
Purchase #4	$43.38	4.622%	$45.385	$45.39	$45.40	$45.40
Purchase #5	$170.87	8.674%	$185.6913	$185.69	$185.70	$185.70
Purchase #6	$246.45	6.696%	$262.9523	$262.95	$262.95	$263.00
Purchase #7	$245.42	10.297%	$270.6909	$270.69	$270.70	$270.70
7 purchase totals =	$960.19		$1,047.3399	$1,047.34	$1,047.35	$1,047.40