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	$197.63	7.122%	$211.7052	$211.71	$211.70	$211.70
Purchase #2	$86.95	8.541%	$94.3764	$94.38	$94.40	$94.40
Purchase #3	$81.94	4.216%	$85.3946	$85.39	$85.40	$85.40
Purchase #4	$242.96	12.669%	$273.7406	$273.74	$273.75	$273.70
Purchase #5	$109.40	3.574%	$113.31	$113.31	$113.30	$113.30
Purchase #6	$213.62	4.142%	$222.4681	$222.47	$222.45	$222.50
Purchase #7	$179.63	5.851%	$190.1402	$190.14	$190.15	$190.10
7 purchase totals =	$1,112.13		$1,191.1351	$1,191.14	$1,191.15	$1,191.10