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	$98.25	4.779%	$102.9454	$102.95	$102.95	$102.90
Purchase #2	$60.77	7.604%	$65.391	$65.39	$65.40	$65.40
Purchase #3	$200.51	5.361%	$211.2593	$211.26	$211.25	$211.30
Purchase #4	$92.40	3.276%	$95.427	$95.43	$95.45	$95.40
Purchase #5	$69.76	12.755%	$78.6579	$78.66	$78.65	$78.70
Purchase #6	$10.36	7.638%	$11.1513	$11.15	$11.15	$11.20
Purchase #7	$60.37	11.635%	$67.394	$67.39	$67.40	$67.40
7 purchase totals =	$592.42		$632.2259	$632.23	$632.25	$632.30