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	$114.91	4.349%	$119.9074	$119.91	$119.90	$119.90
Purchase #2	$225.50	7.666%	$242.7868	$242.79	$242.80	$242.80
Purchase #3	$217.95	12.336%	$244.8363	$244.84	$244.85	$244.80
Purchase #4	$17.46	7.511%	$18.7714	$18.77	$18.75	$18.80
Purchase #5	$46.92	12.873%	$52.96	$52.96	$52.95	$53.00
Purchase #6	$166.89	4.757%	$174.829	$174.83	$174.85	$174.80
Purchase #7	$152.92	12.120%	$171.4539	$171.45	$171.45	$171.50
7 purchase totals =	$942.55		$1,025.5448	$1,025.55	$1,025.55	$1,025.60