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	$248.80	3.219%	$256.8089	$256.81	$256.80	$256.80
Purchase #2	$54.51	13.648%	$61.9495	$61.95	$61.95	$61.90
Purchase #3	$183.96	6.556%	$196.0204	$196.02	$196.00	$196.00
Purchase #4	$172.88	10.680%	$191.3436	$191.34	$191.35	$191.30
Purchase #5	$33.94	4.552%	$35.4849	$35.48	$35.50	$35.50
Purchase #6	$194.38	8.816%	$211.5165	$211.52	$211.50	$211.50
Purchase #7	$65.44	7.597%	$70.4115	$70.41	$70.40	$70.40
7 purchase totals =	$953.91		$1,023.5353	$1,023.53	$1,023.50	$1,023.40