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	$215.85	7.523%	$232.0884	$232.09	$232.10	$232.10
Purchase #2	$91.39	9.222%	$99.818	$99.82	$99.80	$99.80
Purchase #3	$207.69	7.441%	$223.1442	$223.14	$223.15	$223.10
Purchase #4	$18.70	9.425%	$20.4625	$20.46	$20.45	$20.50
Purchase #5	$131.33	9.654%	$144.0086	$144.01	$144.00	$144.00
Purchase #6	$179.89	5.199%	$189.2425	$189.24	$189.25	$189.20
Purchase #7	$146.89	6.755%	$156.8124	$156.81	$156.80	$156.80
7 purchase totals =	$991.74		$1,065.5766	$1,065.57	$1,065.55	$1,065.50