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	$192.70	11.319%	$214.5117	$214.51	$214.50	$214.50
Purchase #2	$129.28	7.710%	$139.2475	$139.25	$139.25	$139.20
Purchase #3	$223.86	3.428%	$231.5339	$231.53	$231.55	$231.50
Purchase #4	$224.59	13.334%	$254.5368	$254.54	$254.55	$254.50
Purchase #5	$59.83	9.175%	$65.3194	$65.32	$65.30	$65.30
Purchase #6	$29.50	6.174%	$31.3213	$31.32	$31.30	$31.30
Purchase #7	$82.28	7.315%	$88.2988	$88.30	$88.30	$88.30
7 purchase totals =	$942.04		$1,024.7694	$1,024.77	$1,024.75	$1,024.60