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	$128.76	11.478%	$143.5391	$143.54	$143.55	$143.50
Purchase #2	$5.44	6.618%	$5.8	$5.80	$5.80	$5.80
Purchase #3	$162.61	10.827%	$180.2158	$180.22	$180.20	$180.20
Purchase #4	$233.90	4.817%	$245.167	$245.17	$245.15	$245.20
Purchase #5	$165.50	5.448%	$174.5164	$174.52	$174.50	$174.50
Purchase #6	$93.76	6.144%	$99.5206	$99.52	$99.50	$99.50
Purchase #7	$165.93	8.213%	$179.5578	$179.56	$179.55	$179.60
7 purchase totals =	$955.90		$1,028.3167	$1,028.33	$1,028.25	$1,028.30