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	$119.70	3.567%	$123.9697	$123.97	$123.95	$124.00
Purchase #2	$14.59	11.621%	$16.2855	$16.29	$16.30	$16.30
Purchase #3	$239.45	11.626%	$267.2885	$267.29	$267.30	$267.30
Purchase #4	$250.44	6.661%	$267.1218	$267.12	$267.10	$267.10
Purchase #5	$160.88	7.215%	$172.4875	$172.49	$172.50	$172.50
Purchase #6	$152.34	8.516%	$165.3133	$165.31	$165.30	$165.30
Purchase #7	$131.26	6.643%	$139.9796	$139.98	$140.00	$140.00
7 purchase totals =	$1,068.66		$1,152.4459	$1,152.45	$1,152.45	$1,152.50