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	$110.95	4.676%	$116.138	$116.14	$116.15	$116.10
Purchase #2	$172.30	3.614%	$178.5269	$178.53	$178.55	$178.50
Purchase #3	$38.79	12.143%	$43.5003	$43.50	$43.50	$43.50
Purchase #4	$99.77	5.124%	$104.8822	$104.88	$104.90	$104.90
Purchase #5	$156.61	12.154%	$175.6444	$175.64	$175.65	$175.60
Purchase #6	$106.51	4.388%	$111.1837	$111.18	$111.20	$111.20
Purchase #7	$69.41	11.139%	$77.1416	$77.14	$77.15	$77.10
7 purchase totals =	$754.34		$807.0171	$807.01	$807.10	$806.90