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	$41.31	8.755%	$44.9267	$44.93	$44.95	$44.90
Purchase #2	$178.97	9.825%	$196.5538	$196.55	$196.55	$196.60
Purchase #3	$241.87	8.362%	$262.0952	$262.10	$262.10	$262.10
Purchase #4	$97.56	11.656%	$108.9316	$108.93	$108.95	$108.90
Purchase #5	$93.28	13.330%	$105.7142	$105.71	$105.70	$105.70
Purchase #6	$111.93	5.795%	$118.4163	$118.42	$118.40	$118.40
Purchase #7	$94.53	10.681%	$104.6267	$104.63	$104.65	$104.60
7 purchase totals =	$859.45		$941.2645	$941.27	$941.30	$941.20