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	$59.43	5.578%	$62.745	$62.75	$62.75	$62.70
Purchase #2	$98.87	6.274%	$105.0731	$105.07	$105.05	$105.10
Purchase #3	$143.46	6.226%	$152.3918	$152.39	$152.40	$152.40
Purchase #4	$27.52	5.507%	$29.0355	$29.04	$29.05	$29.00
Purchase #5	$216.94	11.606%	$242.1181	$242.12	$242.10	$242.10
Purchase #6	$215.32	3.675%	$223.233	$223.23	$223.25	$223.20
Purchase #7	$125.75	4.434%	$131.3258	$131.33	$131.35	$131.30
7 purchase totals =	$887.29		$945.9223	$945.93	$945.95	$945.80