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	$211.49	9.657%	$231.9136	$231.91	$231.90	$231.90
Purchase #2	$29.90	11.554%	$33.3546	$33.35	$33.35	$33.40
Purchase #3	$216.85	11.736%	$242.2995	$242.30	$242.30	$242.30
Purchase #4	$164.48	3.555%	$170.3273	$170.33	$170.35	$170.30
Purchase #5	$61.35	8.141%	$66.3445	$66.34	$66.35	$66.30
Purchase #6	$181.38	8.544%	$196.8771	$196.88	$196.90	$196.90
Purchase #7	$99.47	11.608%	$111.0165	$111.02	$111.00	$111.00
7 purchase totals =	$964.92		$1,052.1331	$1,052.13	$1,052.15	$1,052.10