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	$145.54	11.691%	$162.5551	$162.56	$162.55	$162.60
Purchase #2	$93.88	12.866%	$105.9586	$105.96	$105.95	$106.00
Purchase #3	$89.34	12.758%	$100.738	$100.74	$100.75	$100.70
Purchase #4	$177.78	3.838%	$184.6032	$184.60	$184.60	$184.60
Purchase #5	$207.93	7.578%	$223.6869	$223.69	$223.70	$223.70
Purchase #6	$29.50	9.290%	$32.2406	$32.24	$32.25	$32.20
Purchase #7	$203.41	4.668%	$212.9052	$212.91	$212.90	$212.90
7 purchase totals =	$947.38		$1,022.6876	$1,022.70	$1,022.70	$1,022.70