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	$197.66	4.142%	$205.8471	$205.85	$205.85	$205.80
Purchase #2	$72.27	7.126%	$77.42	$77.42	$77.40	$77.40
Purchase #3	$64.46	12.108%	$72.2648	$72.26	$72.25	$72.30
Purchase #4	$170.26	7.202%	$182.5221	$182.52	$182.50	$182.50
Purchase #5	$97.97	10.717%	$108.4694	$108.47	$108.45	$108.50
Purchase #6	$212.76	7.705%	$229.1532	$229.15	$229.15	$229.20
Purchase #7	$171.86	11.202%	$191.1118	$191.11	$191.10	$191.10
7 purchase totals =	$987.24		$1,066.7884	$1,066.78	$1,066.70	$1,066.80