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	$194.89	4.793%	$204.2311	$204.23	$204.25	$204.20
Purchase #2	$57.69	7.116%	$61.7952	$61.80	$61.80	$61.80
Purchase #3	$69.64	10.735%	$77.1159	$77.12	$77.10	$77.10
Purchase #4	$248.29	12.222%	$278.636	$278.64	$278.65	$278.60
Purchase #5	$75.51	9.333%	$82.5573	$82.56	$82.55	$82.60
Purchase #6	$161.53	4.745%	$169.1946	$169.19	$169.20	$169.20
Purchase #7	$174.70	6.422%	$185.9192	$185.92	$185.90	$185.90
7 purchase totals =	$982.25		$1,059.4493	$1,059.46	$1,059.45	$1,059.40