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	$174.70	7.554%	$187.8968	$187.90	$187.90	$187.90
Purchase #2	$191.37	7.825%	$206.3447	$206.34	$206.35	$206.30
Purchase #3	$134.56	13.194%	$152.3138	$152.31	$152.30	$152.30
Purchase #4	$66.36	3.766%	$68.8591	$68.86	$68.85	$68.90
Purchase #5	$234.56	13.556%	$266.357	$266.36	$266.35	$266.40
Purchase #6	$135.27	13.323%	$153.292	$153.29	$153.30	$153.30
Purchase #7	$176.96	7.633%	$190.4674	$190.47	$190.45	$190.50
7 purchase totals =	$1,113.78		$1,225.5308	$1,225.53	$1,225.50	$1,225.60