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	$221.43	10.389%	$244.4344	$244.43	$244.45	$244.40
Purchase #2	$38.88	6.125%	$41.2614	$41.26	$41.25	$41.30
Purchase #3	$45.30	11.326%	$50.4307	$50.43	$50.45	$50.40
Purchase #4	$145.35	6.344%	$154.571	$154.57	$154.55	$154.60
Purchase #5	$136.42	11.347%	$151.8996	$151.90	$151.90	$151.90
Purchase #6	$195.48	13.171%	$221.2267	$221.23	$221.25	$221.20
Purchase #7	$171.74	9.126%	$187.413	$187.41	$187.40	$187.40
7 purchase totals =	$954.60		$1,051.2368	$1,051.23	$1,051.25	$1,051.20