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	$228.79	7.678%	$246.3565	$246.36	$246.35	$246.40
Purchase #2	$85.64	10.768%	$94.8617	$94.86	$94.85	$94.90
Purchase #3	$89.58	5.113%	$94.1602	$94.16	$94.15	$94.20
Purchase #4	$62.59	8.373%	$67.8307	$67.83	$67.85	$67.80
Purchase #5	$242.74	11.607%	$270.9148	$270.91	$270.90	$270.90
Purchase #6	$83.67	6.110%	$88.7822	$88.78	$88.80	$88.80
Purchase #7	$214.42	13.571%	$243.5189	$243.52	$243.50	$243.50
7 purchase totals =	$1,007.43		$1,106.4250	$1,106.42	$1,106.40	$1,106.50