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	$44.37	5.497%	$46.809	$46.81	$46.80	$46.80
Purchase #2	$105.79	3.845%	$109.8576	$109.86	$109.85	$109.90
Purchase #3	$239.66	10.274%	$264.2827	$264.28	$264.30	$264.30
Purchase #4	$128.68	8.445%	$139.547	$139.55	$139.55	$139.50
Purchase #5	$185.89	6.149%	$197.3204	$197.32	$197.30	$197.30
Purchase #6	$221.71	9.217%	$242.145	$242.15	$242.15	$242.10
Purchase #7	$35.55	5.472%	$37.4953	$37.50	$37.50	$37.50
7 purchase totals =	$961.65		$1,037.4570	$1,037.47	$1,037.45	$1,037.40