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	$94.43	4.380%	$98.566	$98.57	$98.55	$98.60
Purchase #2	$199.64	6.647%	$212.9101	$212.91	$212.90	$212.90
Purchase #3	$35.48	4.732%	$37.1589	$37.16	$37.15	$37.20
Purchase #4	$195.50	5.308%	$205.8771	$205.88	$205.90	$205.90
Purchase #5	$53.50	3.419%	$55.3292	$55.33	$55.35	$55.30
Purchase #6	$205.62	9.817%	$225.8057	$225.81	$225.80	$225.80
Purchase #7	$171.57	5.398%	$180.8313	$180.83	$180.85	$180.80
7 purchase totals =	$955.74		$1,016.4783	$1,016.49	$1,016.50	$1,016.50