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	$112.32	11.704%	$125.4659	$125.47	$125.45	$125.50
Purchase #2	$245.55	11.504%	$273.7981	$273.80	$273.80	$273.80
Purchase #3	$82.58	7.241%	$88.5596	$88.56	$88.55	$88.60
Purchase #4	$160.61	3.135%	$165.6451	$165.65	$165.65	$165.60
Purchase #5	$229.44	11.319%	$255.4103	$255.41	$255.40	$255.40
Purchase #6	$189.64	3.453%	$196.1883	$196.19	$196.20	$196.20
Purchase #7	$58.35	8.867%	$63.5239	$63.52	$63.50	$63.50
7 purchase totals =	$1,078.49		$1,168.5912	$1,168.60	$1,168.55	$1,168.60