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	$86.31	6.863%	$92.2335	$92.23	$92.25	$92.20
Purchase #2	$21.42	4.242%	$22.3286	$22.33	$22.35	$22.30
Purchase #3	$53.56	11.456%	$59.6958	$59.70	$59.70	$59.70
Purchase #4	$76.73	4.755%	$80.3785	$80.38	$80.40	$80.40
Purchase #5	$174.89	9.718%	$191.8858	$191.89	$191.90	$191.90
Purchase #6	$104.58	5.555%	$110.3894	$110.39	$110.40	$110.40
Purchase #7	$5.62	9.334%	$6.1446	$6.14	$6.15	$6.10
7 purchase totals =	$523.11		$563.0562	$563.06	$563.15	$563.00