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	$195.72	10.488%	$216.2471	$216.25	$216.25	$216.20
Purchase #2	$42.42	11.839%	$47.4421	$47.44	$47.45	$47.40
Purchase #3	$116.50	3.736%	$120.8524	$120.85	$120.85	$120.90
Purchase #4	$130.90	8.356%	$141.838	$141.84	$141.85	$141.80
Purchase #5	$247.72	7.108%	$265.3279	$265.33	$265.35	$265.30
Purchase #6	$47.69	8.245%	$51.622	$51.62	$51.60	$51.60
Purchase #7	$159.70	8.256%	$172.8848	$172.88	$172.90	$172.90
7 purchase totals =	$940.65		$1,016.2143	$1,016.21	$1,016.25	$1,016.10