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	$207.44	7.632%	$223.2718	$223.27	$223.25	$223.30
Purchase #2	$196.59	6.776%	$209.9109	$209.91	$209.90	$209.90
Purchase #3	$172.53	7.645%	$185.7199	$185.72	$185.70	$185.70
Purchase #4	$121.36	7.528%	$130.496	$130.50	$130.50	$130.50
Purchase #5	$14.85	6.559%	$15.824	$15.82	$15.80	$15.80
Purchase #6	$48.95	4.386%	$51.0969	$51.10	$51.10	$51.10
Purchase #7	$198.34	11.787%	$221.7183	$221.72	$221.70	$221.70
7 purchase totals =	$960.06		$1,038.0378	$1,038.04	$1,037.95	$1,038.00