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	$181.30	8.303%	$196.3533	$196.35	$196.35	$196.40
Purchase #2	$247.38	11.526%	$275.893	$275.89	$275.90	$275.90
Purchase #3	$130.61	3.611%	$135.3263	$135.33	$135.35	$135.30
Purchase #4	$217.30	7.335%	$233.239	$233.24	$233.25	$233.20
Purchase #5	$226.45	8.535%	$245.7775	$245.78	$245.80	$245.80
Purchase #6	$186.67	7.318%	$200.3305	$200.33	$200.35	$200.30
Purchase #7	$45.80	3.845%	$47.561	$47.56	$47.55	$47.60
7 purchase totals =	$1,235.51		$1,334.4806	$1,334.48	$1,334.55	$1,334.50