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	$184.91	7.576%	$198.9188	$198.92	$198.90	$198.90
Purchase #2	$189.74	4.667%	$198.5952	$198.60	$198.60	$198.60
Purchase #3	$47.30	10.430%	$52.2334	$52.23	$52.25	$52.20
Purchase #4	$225.29	5.184%	$236.969	$236.97	$236.95	$237.00
Purchase #5	$174.46	6.534%	$185.8592	$185.86	$185.85	$185.90
Purchase #6	$64.60	11.341%	$71.9263	$71.93	$71.95	$71.90
Purchase #7	$54.70	11.475%	$60.9768	$60.98	$61.00	$61.00
7 purchase totals =	$941.00		$1,005.4787	$1,005.49	$1,005.50	$1,005.50