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	$115.62	12.454%	$130.0193	$130.02	$130.00	$130.00
Purchase #2	$56.94	6.807%	$60.8159	$60.82	$60.80	$60.80
Purchase #3	$94.83	5.245%	$99.8038	$99.80	$99.80	$99.80
Purchase #4	$131.56	7.718%	$141.7138	$141.71	$141.70	$141.70
Purchase #5	$142.34	6.651%	$151.807	$151.81	$151.80	$151.80
Purchase #6	$228.56	13.729%	$259.939	$259.94	$259.95	$259.90
Purchase #7	$207.34	4.450%	$216.5666	$216.57	$216.55	$216.60
7 purchase totals =	$977.19		$1,060.6654	$1,060.67	$1,060.60	$1,060.60