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	$69.31	4.503%	$72.431	$72.43	$72.45	$72.40
Purchase #2	$113.43	7.350%	$121.7671	$121.77	$121.75	$121.80
Purchase #3	$181.26	10.571%	$200.421	$200.42	$200.40	$200.40
Purchase #4	$39.63	7.233%	$42.4964	$42.50	$42.50	$42.50
Purchase #5	$235.53	5.493%	$248.4677	$248.47	$248.45	$248.50
Purchase #6	$224.71	4.527%	$234.8826	$234.88	$234.90	$234.90
Purchase #7	$110.92	7.194%	$118.8996	$118.90	$118.90	$118.90
7 purchase totals =	$974.79		$1,039.3654	$1,039.37	$1,039.35	$1,039.40