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	$89.64	8.179%	$96.9717	$96.97	$96.95	$97.00
Purchase #2	$184.75	13.154%	$209.052	$209.05	$209.05	$209.10
Purchase #3	$77.72	6.285%	$82.6047	$82.60	$82.60	$82.60
Purchase #4	$188.61	5.321%	$198.6459	$198.65	$198.65	$198.60
Purchase #5	$135.61	6.814%	$144.8505	$144.85	$144.85	$144.90
Purchase #6	$51.30	7.479%	$55.1367	$55.14	$55.15	$55.10
Purchase #7	$100.67	7.372%	$108.0914	$108.09	$108.10	$108.10
7 purchase totals =	$828.30		$895.3529	$895.35	$895.35	$895.40