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	$65.90	10.814%	$73.0264	$73.03	$73.05	$73.00
Purchase #2	$198.27	6.346%	$210.8522	$210.85	$210.85	$210.90
Purchase #3	$189.84	3.533%	$196.547	$196.55	$196.55	$196.50
Purchase #4	$148.28	3.856%	$153.9977	$154.00	$154.00	$154.00
Purchase #5	$38.75	12.133%	$43.4515	$43.45	$43.45	$43.50
Purchase #6	$56.55	13.589%	$64.2346	$64.23	$64.25	$64.20
Purchase #7	$250.58	13.385%	$284.1201	$284.12	$284.10	$284.10
7 purchase totals =	$948.17		$1,026.2295	$1,026.23	$1,026.25	$1,026.20