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	$96.37	13.864%	$109.7307	$109.73	$109.75	$109.70
Purchase #2	$17.80	5.740%	$18.8217	$18.82	$18.80	$18.80
Purchase #3	$232.95	13.623%	$264.6848	$264.68	$264.70	$264.70
Purchase #4	$88.25	4.827%	$92.5098	$92.51	$92.50	$92.50
Purchase #5	$82.89	4.749%	$86.8264	$86.83	$86.85	$86.80
Purchase #6	$229.60	12.706%	$258.773	$258.77	$258.75	$258.80
Purchase #7	$225.45	6.612%	$240.3568	$240.36	$240.35	$240.40
7 purchase totals =	$973.31		$1,071.7032	$1,071.70	$1,071.70	$1,071.70