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	$159.95	5.355%	$168.5153	$168.52	$168.50	$168.50
Purchase #2	$73.69	5.747%	$77.925	$77.93	$77.95	$77.90
Purchase #3	$43.38	4.478%	$45.3226	$45.32	$45.30	$45.30
Purchase #4	$48.34	9.424%	$52.8956	$52.90	$52.90	$52.90
Purchase #5	$151.99	10.256%	$167.5781	$167.58	$167.60	$167.60
Purchase #6	$215.91	13.650%	$245.3817	$245.38	$245.40	$245.40
Purchase #7	$194.56	6.785%	$207.7609	$207.76	$207.75	$207.80
7 purchase totals =	$887.82		$965.3792	$965.39	$965.40	$965.40