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	$227.32	4.837%	$238.3155	$238.32	$238.30	$238.30
Purchase #2	$226.67	7.621%	$243.9445	$243.94	$243.95	$243.90
Purchase #3	$52.52	3.437%	$54.3251	$54.33	$54.35	$54.30
Purchase #4	$13.26	6.765%	$14.157	$14.16	$14.15	$14.20
Purchase #5	$50.38	13.156%	$57.008	$57.01	$57.00	$57.00
Purchase #6	$39.25	10.739%	$43.4651	$43.47	$43.45	$43.50
Purchase #7	$100.33	12.827%	$113.1993	$113.20	$113.20	$113.20
7 purchase totals =	$709.73		$764.4145	$764.43	$764.40	$764.40