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	$162.95	3.728%	$169.0248	$169.02	$169.00	$169.00
Purchase #2	$163.78	5.176%	$172.2573	$172.26	$172.25	$172.30
Purchase #3	$240.59	4.200%	$250.6948	$250.69	$250.70	$250.70
Purchase #4	$40.67	4.578%	$42.5319	$42.53	$42.55	$42.50
Purchase #5	$120.99	12.594%	$136.2275	$136.23	$136.25	$136.20
Purchase #6	$124.50	3.866%	$129.3132	$129.31	$129.30	$129.30
Purchase #7	$154.32	10.810%	$171.002	$171.00	$171.00	$171.00
7 purchase totals =	$1,007.80		$1,071.0515	$1,071.04	$1,071.05	$1,071.00