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	$103.35	8.323%	$111.9518	$111.95	$111.95	$112.00
Purchase #2	$181.43	5.310%	$191.0639	$191.06	$191.05	$191.10
Purchase #3	$94.75	5.456%	$99.9196	$99.92	$99.90	$99.90
Purchase #4	$111.69	11.865%	$124.942	$124.94	$124.95	$124.90
Purchase #5	$234.65	6.851%	$250.7259	$250.73	$250.75	$250.70
Purchase #6	$99.60	9.602%	$109.1636	$109.16	$109.15	$109.20
Purchase #7	$141.48	8.809%	$153.943	$153.94	$153.95	$153.90
7 purchase totals =	$966.95		$1,041.7098	$1,041.70	$1,041.70	$1,041.70