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	$104.40	13.363%	$118.351	$118.35	$118.35	$118.40
Purchase #2	$38.61	10.556%	$42.6857	$42.69	$42.70	$42.70
Purchase #3	$159.46	9.132%	$174.0219	$174.02	$174.00	$174.00
Purchase #4	$136.51	10.419%	$150.733	$150.73	$150.75	$150.70
Purchase #5	$201.88	11.607%	$225.3122	$225.31	$225.30	$225.30
Purchase #6	$168.34	3.675%	$174.5265	$174.53	$174.55	$174.50
Purchase #7	$249.48	11.681%	$278.6218	$278.62	$278.60	$278.60
7 purchase totals =	$1,058.68		$1,164.2521	$1,164.25	$1,164.25	$1,164.20