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	$195.77	10.361%	$216.0537	$216.05	$216.05	$216.10
Purchase #2	$90.32	5.812%	$95.5694	$95.57	$95.55	$95.60
Purchase #3	$55.44	6.247%	$58.9033	$58.90	$58.90	$58.90
Purchase #4	$235.77	3.833%	$244.8071	$244.81	$244.80	$244.80
Purchase #5	$199.36	11.604%	$222.4937	$222.49	$222.50	$222.50
Purchase #6	$18.25	3.501%	$18.8889	$18.89	$18.90	$18.90
Purchase #7	$81.75	9.613%	$89.6086	$89.61	$89.60	$89.60
7 purchase totals =	$876.66		$946.3247	$946.32	$946.30	$946.40