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	$196.80	9.728%	$215.9447	$215.94	$215.95	$215.90
Purchase #2	$227.25	5.806%	$240.4441	$240.44	$240.45	$240.40
Purchase #3	$89.33	4.532%	$93.3784	$93.38	$93.40	$93.40
Purchase #4	$159.45	12.384%	$179.1963	$179.20	$179.20	$179.20
Purchase #5	$225.82	7.817%	$243.4723	$243.47	$243.45	$243.50
Purchase #6	$151.74	8.499%	$164.6364	$164.64	$164.65	$164.60
Purchase #7	$215.33	13.558%	$244.5244	$244.52	$244.50	$244.50
7 purchase totals =	$1,265.72		$1,381.5966	$1,381.59	$1,381.60	$1,381.50