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	$60.89	3.329%	$62.917	$62.92	$62.90	$62.90
Purchase #2	$191.89	8.547%	$208.2908	$208.29	$208.30	$208.30
Purchase #3	$188.54	3.860%	$195.8176	$195.82	$195.80	$195.80
Purchase #4	$222.86	10.700%	$246.706	$246.71	$246.70	$246.70
Purchase #5	$216.34	10.710%	$239.51	$239.51	$239.50	$239.50
Purchase #6	$52.82	3.162%	$54.4902	$54.49	$54.50	$54.50
Purchase #7	$91.59	5.551%	$96.6742	$96.67	$96.65	$96.70
7 purchase totals =	$1,024.93		$1,104.4058	$1,104.41	$1,104.35	$1,104.40