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	$195.57	7.398%	$210.0383	$210.04	$210.05	$210.00
Purchase #2	$89.44	6.738%	$95.4665	$95.47	$95.45	$95.50
Purchase #3	$68.79	3.618%	$71.2788	$71.28	$71.30	$71.30
Purchase #4	$171.78	3.769%	$178.2544	$178.25	$178.25	$178.30
Purchase #5	$105.51	6.474%	$112.3407	$112.34	$112.35	$112.30
Purchase #6	$153.60	4.326%	$160.2447	$160.24	$160.25	$160.20
Purchase #7	$233.63	8.826%	$254.2502	$254.25	$254.25	$254.30
7 purchase totals =	$1,018.32		$1,081.8736	$1,081.87	$1,081.90	$1,081.90