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	$194.65	3.119%	$200.7211	$200.72	$200.70	$200.70
Purchase #2	$78.80	12.847%	$88.9234	$88.92	$88.90	$88.90
Purchase #3	$25.43	8.288%	$27.5376	$27.54	$27.55	$27.50
Purchase #4	$244.52	6.271%	$259.8538	$259.85	$259.85	$259.90
Purchase #5	$150.39	12.385%	$169.0158	$169.02	$169.00	$169.00
Purchase #6	$166.39	11.362%	$185.2952	$185.30	$185.30	$185.30
Purchase #7	$99.83	5.537%	$105.3576	$105.36	$105.35	$105.40
7 purchase totals =	$960.01		$1,036.7045	$1,036.71	$1,036.65	$1,036.70