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	$188.54	5.363%	$198.6514	$198.65	$198.65	$198.70
Purchase #2	$212.41	3.444%	$219.7254	$219.73	$219.75	$219.70
Purchase #3	$189.90	3.373%	$196.3053	$196.31	$196.30	$196.30
Purchase #4	$48.39	8.838%	$52.6667	$52.67	$52.65	$52.70
Purchase #5	$118.51	8.271%	$128.312	$128.31	$128.30	$128.30
Purchase #6	$214.40	13.828%	$244.0472	$244.05	$244.05	$244.00
Purchase #7	$55.56	9.413%	$60.7899	$60.79	$60.80	$60.80
7 purchase totals =	$1,027.71		$1,100.4979	$1,100.51	$1,100.50	$1,100.50